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Colorado Springs 8/19/08 Mini-Meet Report! Woo WA6 maxed vs Single Power and Melos! Also more on Stello DA100 DAC

post #1 of 9
Thread Starter 
Colorado Springs Mini-Meet 8/19/08 with The Headphone Guys (HeadphoneAddict/Larry, and Blutarsky/Scott)

Larry: Blutarsky and I spent the evening comparing my Woo Audio WA6 (with Sylvania 6DE7/Bugle Boy GZ34 - $1250 with all upgrades and the rectifier) with his Melos SHA Gold (retail $1800) and my final production Single Power Square Wave XL balanced but run single ended (est $1500-1700). We used my pair of HD600 with ApureSound V3 cable, and my Grado RS-1 with APS V3 cable. We used Scott’s Stello DA100 DAC fed optical digital by a Macintosh with iTunes, and custom built silver cable RCA interconnects, (and I think the amp selector switch box was made by Mapletree). My XLR interconnects are inexpensive generic cables using Neutrik plugs and jacks.

The reason for a meet so soon after the last one was that we had a couple of questions left over from our last mini-meet. We had observed that the Single Power Square Wave XL driving the HD600 balanced did not sound as open and spacious as the Melos SHA Gold with HD600 plugged into the Melos’ XLR Pre-amp out. Yet when both rigs were running single ended they sounded much closer to each other (I thought they sounded the same while Scott thought the Stello/Mellos was still slightly better single ended.)

It was especially confusing because we were feeding the Single Power via Apogee mini-DAC XLR out for true balanced operation, while the Melos was being fed a single ended input from a Stello DA100 DAC (both hooked to Macintosh computers with the same music, and both upsampling to 192Khz). We wondered if it was a difference in the DAC or the amplifier that was responsible for differences in sound that we heard with both rigs driving the balanced HD600. So, we decided to meet again so we could connect both amps to the same DAC, and try them both with the Balanced HD600 and Grados again.

Scott: Okay let’s get this thing started. Whoops…

Larry: In the previous session Blutarsky and I had also determined that when used with single ended headphones the Single Power and Melos sounded very much alike, and they were both very slightly better than his Zana Deux. I thought that the upper mids of the Zana Deux were just ever so slightly recessed vs the Melos and Single Power when we had listened to them at our last meeting. Otherwise I had nothing to complain about it. But, I wanted to borrow another set of ears to see where my WA6 Maxed stood in the mix. So this time we took the WA6 and inserted it in the place of the Zana Deux which was disconnected (no room for them all). We made sure to use the "8-99 ohm" or "100-600 ohm" impedance switch on the back of the WA6, depending on the headphone being used. We assessed the amps when cold, then at 30-45 minutes, and continued over the next 2 - 2.5 hours, and finished our listening after 3 hours total.

With the amps still cold, the WA6 was initially lacking in some treble sparkle and the soundstage was rather closed in vs the Melos and Single Power. It was actually quite a shock to hear the difference. But we persevered and after 30-45 minutes of warm up the WA6 was right up there with the more expensive amps - with only subtle differences in size of soundstage and ambience between the three amps. Initially with the dull and confined sound of the "cold" WA6 we switched the RS-1 from flats to bowls. We felt that the bowls enhanced the WA6's "cold" soundstage and treble, and the WA6 produces enough bass that we didn't miss anything with bowls. The Melos sounded better when cold, and it was also more open and spacious, thus able to take advantage of the Grado flat pads to increase bass without losing soundstage - but it worked well with bowls too. The remainder of the listening was done with bowl pads on the RS-1, in addition to the HD600 with single ended and balanced cables.

Scott: Makes sense for a tube amp to need the warm-up time, I thought the WA-6 began to sound its best at almost two hours into the session. I’ve noticed the need for warm-up with my other tubers but maybe never noticed such a tremendous difference in performance before. I’d listened to this particular amp before and it sounded like a completely different piece of gear.

Larry: Yep, the WA6 continued to improve during the first 2 hours of warm-up. But it also has had the "Woo Pseudo Dual Power Supply Mod" done to it since the last time you listened to it, so it does sound like a different piece of gear. Some people say that mod is more important than the Vcaps and Blackgates upgrades mine has.

Anyways, after 2 hours of running all the amps, these amps were so close that the only way to easily tell the difference between the WA6 and the Melos or Single Power was to take the headphones off for 30-60 seconds and rest our ears, then plug them into one amp to listen and switch to the other amp after 30 seconds. Doing that, we could hear a slight improvement in substance or body to the music with the Melos and Single Power. But then switching back to the WA6 the second time without resting our ears resulted in the amps sounding pretty much the same again (except the Melos soundstage was still slightly wider, and the Single Power soundstage was slightly taller).

At that point we could switch back and forth over and over again, but felt the differences between the WA6 and the other amps were so small that it had become very difficult to describe the differences. If ever there was a case for warming up some amps longer than expected, this is it! It was at this point that I also started to suspect that the Stello feeding the Single Power and WA6 might be just a little better than my Apogee (which I left at home) in terms of brightness and spaciousness of sound.

Scott: We did a lot of comparative listening during this two-hour period; in retrospect I wish we would have jut let the amps warm up. I think I spent a lot of effort listening to the WA6 and then hearing a different signature every half hour later. Made it difficult to be sure what impressions are valid.

Larry: I agree. Normally at home, I turn it on once and leave it on until the end of the day, so it is warm whenever I want to listen, and I always run music through it for the first 30-40 minutes. Once I am listening I am not paying attention to the gradual changes over the next couple of hours. Doing A/B testing while it warms up really made things harder and accented the changes with warm-up, but now we know better.

Next, before we go on to describing in more detail what we heard with the amps, and what was similar or different, I want to mention a little test we did with the Stello DA100 DAC. This is a great little DAC, with ASRC "up-sampling" to 192Khz sampling-rate, but it includes a bypass switch to turn off up-sampling (unlike the Apogee which is on all the time). We wanted to see if there was a difference with the up-sampling turned on vs "bypass" mode with it off, so once the amps were all warmed up we tried out a couple of things. First, using optical output from the Mac, we switched it on and off and on and off - and despite the approx one second delay in the music restarting we were pretty sure there was minimal change and we liked it both ways. So, we’re both wondering what’s the big deal. Then we connected the Stello to the Mac’s USB too.

With the up-sampling on, and Scott switching the output on the Mac side and me switching the DAC input on my side, going back and forth between optical and USB did not change the sound - yes, optical and USB sounded the same. The Shocker came when we switched to "bypass" mode and turned off the up-sampling while listening to USB. We both agreed the USB input on the Stello suffered in "bypass" mode, with a smaller more constricted soundstage, which opened up noticeably upon leaving "bypass" mode. I also felt the sound was thinner (lacked body) and the music sounded edgier with bypass mode turned on (i.e. up-sampling turned off). With that said, I would seriously question the need to turn off up-sampling, other than if I was mastering a CD and needed to hear a worst case scenario via USB DAC. Don’t get me wrong, USB in bypass mode was very nice, but clearly inferior vs up-sampling turned on.

Scott: I agree the up sampling on the USB output is necessary for this DAC to go from sounding very nice to excellent. I did not really know what to expect when I bought it but I have been very pleased with its performance. I’ve read a few of the Stello-love threads but have not really done any comparative listening until I got my Apogee Duet and recently with Larry’s Apogee mini-DAC. From listening to the SP SQW on the Stello and having heard it sourced by the Apogee mini-DAC I believe the Stello DA-100 is superior to both pieces of Apogee gear.

Larry: So, getting back to studying the amps we left the DAC set for up-sampling, although I do not recall if it was left on optical or USB because they sounded the same.
I thought the WA6 was very balanced sounding, and very refined and detailed. The amp was quick and snappy, with good PRAT, and didn't have any obvious frequency response aberrations. The sound was smooth, without any hint of edginess or harshness. Real instruments (like piano, string bass, drums) all have good timbre, tone and resonance. These things are where all three amps were similar. However, I thought the decay with instruments was slightly quicker in the WA6 than with the Melos or Single Power, leaving a little less sound between notes - which would affect the weight, body or substance of musical instruments. I initially thought this was due to a possible recessed lower mids, but on careful listening nothing was missing, and we couldn’t even hear this every time we switched back and forth between amps. There was still good air and ambience, reflecting the venue of the performance, so I don't think much micro-detail could be missing. Imaging was good, with every instrument having it's own place, but sometimes the musicians sounded like they were rubbing elbows with each other, and the instruments did not always seem to take up as much space as the real thing would. There was great left-right channel separation, although the soundstage was not as tall as the Single Power, nor as wide as the Melos.

Scott: My impressions were hampered by extended warm-up. I’d agree that at the end of the two hour period the WA6 shaped up and I can’t disagree with Larry’s description. I was struck by the narrowness and lack of depth in the soundstage compared to the other two amps. I would not have noticed this however, without an immediate and direct comparison.

Larry: Right - the soundstage is not really lacking until you compare it to the Melos and the Single Power, but I'm told that can be fixed with a Sophia Princess rectifier for $150. So, while we're discussing soundstage – as mentioned previously, when running single ended the Single Power's soundstage was about the same size (depth and width) as the WA6, but somewhat taller, while the Melos soundstage was not as tall as the Single Power but sounded wider and gave the musicians more space for their instruments. I thought the Single Power soundstage was also a little deeper than the others although Scott did not agree. But where the Melos and Single Power clearly stood ahead of the pack was when we changed the HD600 single ended cable to the APS V3 balanced cable with Neutrik XLR plugs. The WA6 is single ended only, and the Melos is single ended but has a "pseudo-balanced" XLR pre-amp out that can still run high-impedance headphones (using an adapter), while the Single Power is a fully balanced 8-channel amplifier (4-channels divided into 2 sub-phases each) with both XLR and RCA inputs. Both amps will convert a single ended input from the Stello into a balanced signal, I think via different techniques - the Single Power will "re-create" the negative phase of the signal from the positive phase, while the Melos uses a phase inverter or splitter before the XLR output section. Using the HD600 with balanced cable, the Single Power and Melos still sounded very close to each other (just like when single ended), but the soundstage and instrument separation were vastly improved over single ended out of ANY of the three amps.

We had plugged the Single Power amp into the XLR jacks in the back of the Melos with generic XLR interconnects using Neutrik plugs, and used the Melos as a pre-amp. This did not change the sound at all vs plugging the HD600 directly into my XLR interconnects with the SP amp removed (this way the only variable was the amps not the interconnects). We even ran one channel through the SP amp and one channel without it, by plugging the headphones directly into the interconnect on one channel, and they still sounded the same (we swapped channels and still sounded the same). The Single Power was basically what others have referred to as a "wire with gain".

Removing my XLR interconnects from the equation, and plugging the HD600 directly into the Melos XLR jacks made a dramatic improvement on top of the previous improvement - but the Single Power again sounded just like the Melos when we plugged it directly into the Stello with identical custom made silver RCA interconnects like those used to feed the Melos (we pulled out the WA6 to do this part). I was more than a little disappointed to hear just how bad the generic XLR interconnects that I got free with my Apogee sounded. I had another pair of new XLR with Cardas wire and Neutrik connectors with me, but we got a ground loop with them even though a brief test at my home had no such issue. Scott has some stranded silver cable XLR interconnects coming soon that we will have to try next time, and once I am done paying off my new Woo GES I can buy some better XLR interconnects for myself (anti-cables IC’s here I come).

Scott: Comparisons from the single-ended outputs were tough to put into words, there wasn’t much differentiating the amps, plus we introduced a variable with flat and bowl pads on the RS-1 early when the WA6 didn’t feel its best. I’d say the biggest difference between the amps was in the lower ranges and soundstage. I felt the WA6 had the most compressed soundstage and it was more difficult to place the instruments in their positions on stage. I may not have made this observation without this opportunity to compare some unique amps side by side. I felt the SP SQW was more expansive (maybe 20%) than the WA6 in all dimensions and also had more bass impact than the WA6. The Melos soundstage sounded wider (another 15%) and also deeper (maybe 10%) but not as vertical. This is hard to describe because the height of the soundstage was really apparent but It’s the first time I’ve heard that kind of soundstage difference in the same phone. The difference was as big as you’d expect from a closed versus open phone of the same make like a Darth Beyer open vs closed variant Darth. I am a basshead and the bass excellent in both the SP SQW and the melos – both amps handled the string bass on Tsuyoshi Yamamoto "Misty" on the Autumn in Seattle offering. Even to the extent that the slight rattle on "something in the studio" during the (I think – can’t hear it now on a B737 with my Westone ES2) first thirty seconds or so is apparent to the same degree with both amps. I never heard that studio artifact with the same clarity before using these two amps.

Larry: I think what it comes down to is asking ourselves, what happens when we didn't try to analyze every little thing we heard, but focused on the musical performance instead? I think we both felt that the Single Power and Melos offered a vague but very slightly improved feeling of actually being in the room with the musicians vs the WA6 when driving single ended HD600 and RS-1, but with no real way to describe why because the WA6 didn't do anything particularly wrong that we could pin down. I would venture to say that the differences we heard in the WA6 tonight were very much like the ones we heard in the Zana Deux last time, in that the musicians and instruments felt very slightly less solid than when played through the Melos or Single Power. Based on what I heard with the WA6 vs the other amps this time, I think I can safely say that the WA6 would probably match the performance of the Zana Deux without a problem. I thought the WA6 was at least 96-97% of the sound of the Melos or Single Power , when we listened single ended via 1/4" jack. This is lofty company that the WA6 holds.

Scott: Dude, now we’re going to have to review the ZD and WA6 before I make my move to sell her. Since I’m out of town for a few weeks that will have to wait, but I think you just issued a challenge. I’d really be surprised if the WA6 is up to that comparison but now you’ve got me curious. Lets talk faux balanced... ..BTW, my sweet silver Pendles xlr interconnects came in the day after we tore my cabinet apart to do this meet.

Larry: Well, maybe the Zana Deux will have a more expansive soundstage until I upgrade my rectifier - but I think we both agree that changing to the balanced HD600 with APS V3 cable puts the Melos and Single Power over the top, and seriously challenges anything I have heard for their ability to more fully immerse you in the musical experience. I definitely regretted not having any hi-end XLR interconnects yet, and I am hoping that my Apogee mini-DAC will be up to the task once I get them. For now I come away from the greatly impressed by the Stello DA100, despite all the high praise I have for my Apogee.

Scott: I hate to say it partner but we connected the Apogee with RCA/XLR connector via the same interconnects that we used on this test, and it didn’t change the performance audibly – but let’s test that next time too – its possible the cheap XLR>RCA connector adaptors impacted the signal.

I think the "pinch me I’m dreaming" award goes equally to the Single Power SQW and to discovering the xlr outs on the back of the Melos. I’m not going to say that it is better in any way than the SQW because even if my ears weren’t so fried by this time, I was enjoying the music so much I could not have cared a whit. In numerous tests hooking the R channel to the Melos, the L channel to the SP with balance and volumes matched we could not distinguish the two amps. We switched channels and tried again - same result.

Now the last time we did this test the single power SQW was fed from a true balanced source via the Apogee mini-DAC and the Melos was fed single-ended from the Stello. We listened to the HD600 via the Melos faux balanced outputs (which are not rated to drive headphones). Last time I though the Melos easily outperformed the SP SQW, I was pretty happy by the result. This time with the Stello driving both amps, it was clear to me the shortfall was the Apogee Mini-Dac (or the XLR Connectors – for Larry’s sake) because on the Stello, thsy both sounded wonderful. I mean HE-60 wonderful, in fact I think we need to compare that next time because I think the Stello > SPSQW/Melos > balanced HD600 combo sounds like the HE60 with the bass impact that was missing in the HE60. So many challenges – so little time to listen and compare them.

Larry: Yeah, and the single ended testing that included the WA6 also left me wishing I had brought my Phillips 1955 Metal Base GZ34 for the WA6, or that I owned a Sophia Princess or Emission Labs 5U4G to try in the WA6 (I also have 2 cheaper 5U4G and 3 more pairs of 6DE7 from RCA, GE and Raytheon that I didn't get to bring). So the two of us will be meeting again in the near future, and I will bring all my rectifiers and 6DE7 tubes to see if we can tune the WA6 to sound just like the best of them. Scott told me the Zana Deux is going up for sale, so he may not have it the next time we meet; but if it is still available I would like to pit the WA6 against the Zana Deux as well.

Scott: Oh I’ll have her; I’m getting cold feet thinking about selling her. I may have to sacrifice one of the three kings instead. It’s crazy because each amp has its place with each phone and who can decide? I just have so little time to spend with my gear right now (small kids) that great equipment sits and is not being used – tough to justify the investment when it’s inactive. Plus, the performance of the underpowered and severely misused Melos faux output has me thinking there may be an EC Balancing Act in my future. Man solving my newfound balanced lust with a big iron Eddie Current solution could be just what the doctor ordered (uh -right Larry?).

Larry: Well, I think the Melos drives the balanced HD600 well enough that you should nip that thought in the bud. It seems that you are having as hard of a time dealing with the thought of parting with the Zana Deux as I am with parting with the WA6 - we both have another amp that slightly outperforms the "spare" yet we are attached to our spare amps. I also might have to spend more time with those PS-1 of yours, and who knows, maybe they'll go home with me someday. I just don't know that I can part with my HE60/HEV70 to trade for them, and don't know that I can part with the cash either.

So, We're at the end of our rambli... er I mean musings. Somehow we were both feeling burned out after just three hours of listening, to the point that I cannot be sure what I told Scott was my favorite amp for the RS-1 or HD600 single ended. I think with the single ended HD600 I slightly preferred the Single Power for the taller deeper soundstage and more substance to the instruments, but with RS-1/flats the Melos was my preferred amp as the flats feed my latent bass-head tendencies and the amp still gives a nice soundstage with flats. With RS-1 and bowls, I couldn’t decide between them most of the time (once fatigue set in they all sounded the same). Going directly from Stello to Single Power with silver interconnects and driving the HD600 balanced - that beat the RS-1 out of any amp. Going from Stello > Melos > HD600 balanced tied with the Single Power as the best, but I thought there may have been a hint of more bass with the Single Power that Scott didn't hear.

Scott: Again folks - do not try these comparisons at home, they are dangerous and costly - both financially and mentally. Besides who out there is saying – "If I only had a Stello, Single Power SQW AND TTVJ flats – instead of this WAS6, Apogee mini-Dac AND crummy grado bowls - Dang!" If such a person is out there, I pity you. However PM me, I think you’ve found your support group with Larry and me.

Larry and Scott: So that’s it for this episode of The Headphone Guys. Stay tuned next time when we make eggs benedict off the top of a fully warmed up and recently cryo’d Melos chassis and an uncryo’d WA6, to see which cooks faster, with less mess!
post #2 of 9
This was a treat to read, guys.
post #3 of 9
Where in Colorado Springs do you hold these meets?
post #4 of 9
Thread Starter 
We pick someone's house, depending on who has the most equipment that would be too hard to move. Most of them are at Blutarsky's but with the early one we had at my house we didn't do a write-up.
post #5 of 9
Wonderful read, Larry.
Quick question on upsampling optical versus USB. Do you know if MAC upsamples data on toslink output, may be that's the reason bypassing upsampling on Stello didn't make any difference, the input signal was already upsampled.
post #6 of 9
Thread Starter 
With Mac, you can open "audio midi" application and set the OS for 24/96 optical, but it defaults to 16/44.1 for optical and USB if you don't mess with it. For years I didn't even know this existed. I don't know what Scott had his set for.

If this change is made before opening itunes, I think I tunes might up-sample and is supposed to do a good job of it, but I am never sure how much I hear a difference. If it is not to make it do up sampling, it at least prevents iTunes from down-sampling a native 24/96 file down to 16/44.1

My Apogee and Headroom both will accept 24/96, but my iBasso D1 would only do 24/48 via optical.
post #7 of 9
Where are the pictures!
post #8 of 9
Thread Starter 
We're bad about photos, although we did remember to get them for the 7/13/08 meet - you can see those....
post #9 of 9
Thread Starter 
So, at the next meet we'll be testing interconnect cables and pitting the WA6 vs Zana Deux directly, since both of them failed to top the Melos and Single Power. I will have several new tubes for the WA6 to try out, that are supposed to open the soundstage noticeably.

The lack of RCA out is a definite issue with the Apogee mini-DAC in trying to test interconnects, because it is possible that any mini-RCA adapter, or XLR-RCA adapter can interfere with the results. That was a little irritating, so we decided to try and compare several XLR interconnects to their RCA counterparts at our next mini-meet soon.

This will make it easier to see if the Stello DA100 DAC is really that much better in sparkle and soundstage than Apogee, or if I just didn't have the right interconnects for my Apogee to compete with the DA100. And, we decided to not use ANY XLR>RCA adapters. So, we needed two pairs of each kind of IC we will be testing, one with XLR for the Apogee, and one with RCA for the Stello. My SP amp can take RCA inputs and convert the signal to balanced, and those RCA cables will let it be used with the Stello, while the XLR will be to connect the SP amp to the Apogee.

So, blutarsky got some custom made silver XLR interconnects to go with the silver RCA cables that we already tried. And I have mmwwhats making me a pair of solid dead silver XLR and RCA IC's too (around $100 for both pair). I have a pair of Anti-cables RCA and XLR here now that sound great as they burn-in. I also have the highflyin9 RCA silver plated copper IC, and a $60 eBay RCA silver plated copper, and a $14 RCA silver plated copper from parts express to be the counterpart to my silver plated XLR that came with my used Apogee (the ones in this mini-meet that didn't perform so well).

In previous testing the Anti-IC RCA cables beat a pair of silver plated copper RCA cables, so it will be interesting to see what results we come up with. As for Apogee vs Stello, I have read Iron_Dreamer's review many times, and don't see that the differences we are hearing could all be attributed to only the DACs. If they are, then I need a DA100 for myself (or DA100 Signature - but no money for either since I ordered a maxed Woo GES)!
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Head-Fi.org › Forums › Meets, Get-Togethers, Factory Tours › Head-Fi Meet Impressions, Trade Show Reports, Factory Tours › Colorado Springs 8/19/08 Mini-Meet Report! Woo WA6 maxed vs Single Power and Melos! Also more on Stello DA100 DAC