[MohawkUS]

As another newcomer to Bakoon(HPA-01 here) I wanted to quickly detail my early impressions on the Bakoon with my Ultrasone Edition 12s.

Firstly I will say that I disagree with anyone who labels this amp as bright, I hear a bit of darkness as other posters have mentioned. Secondly I prefer the voltage output without question. The ED12 has the flattest impedance curves of any of the high-end dynamic headphones I have seen; but the small hills it has can clearly be heard out of the current output. And the effect this adds to the sound makes it sound incoherent to me. Sadly, whilst I have a lot of play in the volume on current(which has a very gradual raising of volume) I am limited to a tiny area a little too close to where channel imbalance sets in on the voltage. For that fact alone I may choose not to keep the amplifier.

I don't have any complaints about the sound, though I'm also not as impressed as I feel that I should be with such a leap over my previous equipment. Yes, the cliche of hearing new things for the first time implies; but I've been using sub-par and vintage equipment for some time. I expect more than just 'more detail.' Things like better soundstaging and a more accurate timbre should be leaps and bounds better than my old equipment. Timbre is much nicer do to not having grain in the sound(the power in my house is poor, so here's one advantage to a battery supply) but soundstaging seems worse than my old equipment. For clarity's sake I am testing with an Ultra-Fi DAC41 and Resonance Labs Herus. The UF is by far the more expensive but it is the worse performer of the two. I'll be testing with some analog sources in the future week. I don't expect to hear anything drastically different however as I have built my system in a way where the sources are quite similar in sound, if anything the analog sources may go a bit further in the 'too dark' direction for my taste.

 

[Sonido]

I have to say I like what the HPA-01 current mode does to my Shure SRH1540 more so than the HD800 so far. The Shure has a pretty flat impedance curve as well, and is low impedance and closed-back. The frequency graph is quite similar to the TH900. Perhaps that's why I find it to synergize so well?

 

[Revogamer]

May pay to split off the HPA-01 impressions into another thread?

Am looking at listening to both the 21 and 01 very soon.. will post impressions myself

 

[Soned]

  May pay to split off the HPA-01 impressions into another thread?

Am looking at listening to both the 21 and 01 very soon.. will post impressions myself

I agree about splitting

 

[Sonido]

Does anyone find there to be a pop through headphones plugged in when powering on the amp? It doesn't sound as strong as some other amps that do it, but it's still there. Do you guys unplug the headphones just to turn it on and then plug it back in?

 

[mscott58]

Sonido - Just checked on my HPA-21 and didn't have any strong pop, just the normal sound I've heard with most gear. In fact the sound of the physical switch being thrown is just as loud (which isn't loud at all) as the electrical sound through the cans. That's with my open LCD-3's. Nothing I'm worried about. Hope this helps! mscott

 

[Justin_Time]

  Does anyone find there to be a pop through headphones plugged in when powering on the amp? It doesn't sound as strong as some other amps that do it, but it's still there. Do you guys unplug the headphones just to turn it on and then plug it back in?

No, absolutely no pop here!
 
Did you have the volume down all the way when you turned the unit on?  I assume you did. 
 
Try chasing down the ground demon.  Have everything plugged into the the same power conditioner or float everything and have only one single ground to the AC.

 

[Currawong]

Note that this thread was created from discussion in the HPA-21 thread from about this post: http://www.head-fi.org/t/664097/bakoon-hpa-21-headphone-amplifier/435#post_10792882

 

[komomai]

So I just received my HPA-01 and I'm trying to hook it up to my MacBook Pro so I can listen to it at work.  What kind of cabling would I need?  I've tried the headphone out jack to the right and left phono plugs but no sound.  Sorry for the lame post, but any help would be appreciated.  I've gotten used to the USB cable to the dac/amps combination.  Mahalo for any help.

 

[komomai]

Just received my today, yes I can hear a popping sound when switching on the power.  So I figure I'll just unplug my phones and plug them in when ever I cycle the power.

 

[komomai]

Please ignore my post about not being able to hookup to a MacBook Pro, working great just have my Shure SE-846 IEM to test with and I'm getting blown away with gobs of detail.  Listening to Daniel Ho Watercolors, man so far I'm loving the HPA-01.  Can't wait to try it with the Fostex TH900 and HiFi Man HE500.

 

[LCfiner]

OK, my HPA-01 arrived and here’s my first impressions with the Grado PS1000. I’ve been listening for about an hour and I’ve had it running with the headphones for around 2 hours. Since these are very early impressions, I’m just gonna use bullet point form. I tried to volume match with pink noise as close as possible.
 
baseline. MAD Ear+ HD amp.
- smooth sound, no shout or sibilance. bass is not too impactful but has some slight overhang to notes.
-clear imaging, great soundstage. excellent, clear midrange.
 
HPA-01 current output
- Much bigger bass impact. almost too much as the PS1000 already has a hump at 100 Hz. On some songs, it works very well (single, driving kick drums). But in other cases (overlapping basses or background throbbing bass effects) it can feel overwhelming.
-no sibilance or shout. treble is well controlled.
-similar beautiful midrange as Ear+. nothing missing here.
-similar soundstage.
-the bass kick increase can impact imaging. either positive or negative depending on the track. lots of overlapping bass instruments - not as clear positioning. But for that singular background drum beat, the imaging is very good and the bass instrument feels less “spread out” than Ear+ and more clearly grounded/positioned.
 
HPA-01 voltage output
-can display a little sibilance with the PS1000.
-bass response is in between Ear+ and current output. it has more clean impact than the Ear+ (and with less bloom) but is not nearly as big as current output.
-shorter note overhang for lower mids (only place I’ve noticed it so far). feels tighter and leaner. but this also reduces the sense of warmth and richness. PS1000 does well with the richness but other cans would be better suited to this cleaner sound
-very clear sound. no problems with soundstage or imaging. 
 
I’ll have a cleaner write up in a day or so with some head time with the RS-1i and JH Roxanne as well. so far, it’s the best I’ve heard the PS1000 with the Ear+ being a little better on some of the heavy-bass-in-the-background tracks. 
 
edit: quick impression of JH Roxanne in case anyone was curious.
 
Voltage output sounds best. clear and sharp. bass impacts are tight and impactful.
current output. bass is mushy, bloated and mids feel slow, cupped and/or recessed.
Ear+. mushy bass. mids aren’t as negatively affected as on HPA-01 current output but still bloated.
 
anyway, that didn’t take long. literally the second headphone I plug into the HPA-01 behaves way differently than the PS1000 and much prefers the voltage output.

 

[Gerzom]

I just bought a Bakoon HPA-01 as a replacement for my Mjolnir 

 
 
I'm using Audeze LCD-2.2's and what struck me most with the Bakoon (and made me pull the trigger) was the clarity of the music/sound and all the different layers that I could hear. It lacks a tiny little bit in the lower regions (compared to Mjolnir), but as I'm not a real bass-head, this doesn't bother me. Specially the combination with my vinyl rig is magical. I just had an hour of listening time, but I'll be putting more time on them later tonight.
 
All in all I think this is a real step upwards from the Mjolnir. But looking at the price difference between the 2 amps, I still feel the Mjolnir plays way above it's league (very well done Schiit!!!!)

 

[Sanlitun]

Mine arrived this morning and I was able to spend a little bit of time getting it set up. The thing that struck me the most initially is just how small it is, and having the HPA-01 sitting on top of my NAD M51 makes the NAD look even more ridiculously huge than it already is. I feel the RCA connectors are just a little bit closer together than I would like them on the HPA-01, and if you are using cables with thick jackets or even some WBT locking connectors it might be too snug. I did get my cables connected (KAS Audio Maestro), but the jackets do touch.
 
I tinkered around with it for a bit and have got some settings that seem to sound good, but I can't really do any listening until tonight when it quiets down here and I have some time. So far to get the sound the way I think it should be I have had to adjust the output level on the NAD, and I thought that the LCD-X didn't sound right on the low gain setting, which is a bit of a surprise considering how easy they are to drive.

 

[LCfiner]

I had more time with the HPA-01 and the Ear+ amps. I've used the PS1000, RS1i and the JH Roxanne. DAC is Emotiva DC-1 via USB. I think I've reach some stable conclusions. Nothing has changed drastically form first impressions but I would NOT say the voltage out bass response is "in between" the Ear+ and current output. It's definitely cleaner (less bloom) and has the same or slightly less impact as Ear+, not more.
 
Lots of rambling below...
 
I am focusing on bass response here because all the other major elements I listen for are roughly the same between the amps. There's a solid, wide soundstage, excellent midrange, controlled treble (voltage out feels slightly more trebly here but not piercing) and good resolving capabilties. The only difference I can reliably hear with the PS1000 is the bass difference.
 
The current output with the PS1000 can be either wonderfully energetic and fun or just too bassy - it depends on the song. The issue is the impedence curve of the PS1000. it doubles - from 32 ohm to around 60 ohm - in a narrow spike around 100 Hz. the PS1000 already has a bass hump centered around this frequency.
 
So when the current output interacts with the headphone, it boosts the bass on the PS1000 at 100 Hz by a lot. based on some rough EQ, by around 6 or 8 dB. and the existing  bass hump on the headphone is already pretty big - it doesn't really need extra goosing.
 
So, let's say you get a song that has some melodic midbass that flows under all the other instruments. As an example, I used "Danger and Dread" by Brown Bird. With the HPA-01 current output, the bass is boosted so much that it can overwhelm the rest of the song. it's just too much.
 
Next up, the Ear+ (with a Valvo slanted getter driver tube) also has some bloom with the bass but it's not as big a boost. I'd still like to see bass boost on this song
 
Finally, the voltage output on the HPA-01 has practically no bass boost in this area. the bass is clear and well defined with almost no extra bloom over what the headphone already provides on its own. 
 
So the HPA-01 really feels like two amps in one with the PS1000. the current output creates a big 100 Hz bass boost that can be good for some tracks with driving drumbeats (not accurate, but fun). but it doesn't work with continuous bass guitars or cellos, imo. But the voltage output comes to the rescue with a very clean and tight representation that tames the PS1000s bass. 
 
Now, onto the RS1i. This effect is not seen as drastically on the RS1i because (I think) the impedance increase on the RS1i is only 10 ohm at around 100 Hz (30 to 40ohm). The Bakoon doesn't add a big bass boost. maybe a few dB. And the RS1i has thinner bass than the PS1000 anyway so the effect is just fine. it's a little midbass warmth that adds some body but nothing I find objectionable.
 
Adding another variable to the RS1i, I put on flats and switched out bowls.
 
flat pads + current output = just a bit too bassy and mushy
flat pads + voltage output = sharper and cleaner than either current output or MAD Ear+. very nice. adds some treble energy to the flat pad sound.
 
bowls + current output  = my preferred RS1i combo. adds some body to the sound, but not too much. you get the bigger soundstage over flats.
bowls + voltage output = fine, but a little thin. I find the bowls and RS1 thin on most SS amps so this is really just a less coloured response, I think.
 
Finally, the JH Roxanne. Nothing changed from my initial impressions. They are not usable on the current output, imo. Just too mushy and hollow/echo-y sounding. Very odd interaction. On the Ear+, there's also some mushiness and veil over the mids. 
 
But on the voltage out, they sound the best that I've heard them (used them on AK120, DC-1 amp and iPhone 5, iPod Nano 7G). There's an added snap to the sound that gives it a little bit more energy than I'm used to. I find the Roxanne to have a very lush and warm sound and while the voltage out doesn't rob them of this, it does provide a little extra energy up top that I have not heard from them before. It's really good.
 
But I bought this amp for the PS1000 and now I need to figure out if I prefer keeping the Ear+ and having a slightly gooey sound at all times with the headphones or having the HPA-01 with two different sounds from the two outputs. The current output that's great on maybe 80% of my music and the voltage output for when I need something that leaner in the bass (but is a little too lean for me to want to use it 100% of the time). Do I want to change headphone outputs to deal with this?
 
I know the bakoon is more versatile than the Ear+, just from my experience with these three headphones. And it's better suited for a planar if I ever want to get one of those again in the future. I'm just not sure about using it fulltime with the PS1000. (extra bonus wrinkle - the PS1000e is supposed to have a flatter bass response over the PS1000, so the current output from the HPA-01 might be a better match with the newest iteration, which I want to try one day. hmmm)