Practical Devices XM5 - Page 13

what are the sound characteristics of these different op amps?

My XM5 is on the way to me and I ordered it with the stock op amps and the BUF634 chips.

What I'm looking for is a very warm natural spacious sound that is heavy on the bass.

My IEM's fit the bill in the Atrio M5's to give that but which opamp would further deliver that with the XM5?

So what are the benefits, differences and sound characteristics for the following opamps?


AD8610 WhiteCat
AD8066 WhiteCat
AD8065 WhiteCat

new XM-5 owner

I must say this credit card sized DAC/AMP is just simply amazing. For the size and price, it really packs a lot of punch. Coming from just having a headphone amp running off my iPod LOD's and headphone out on my old Mac Powerbook, the sound quality upgrade has been just staggering. I just couldn't be sure what was making my sound so muddy until I had another DAC to test but I'm absolutely positive that was the weakest link with my existing computer setup. Now I'm just using a small USB powered HDD with my music collection in ALAC and the XM-5 and I'm in audio bliss. It's not perfection, but I'd say it is at least 200% better than the quality coming out of the internal DAC's in any of my computers or iPods and far more of an improvement than I expected.

I too am wondering about these op amp options and whether they are worth extra investment. I look forward to hearing more subjective feedback in this thread

AD8066 is the dual channel version of the AD8065, so not an option for you.

Since the OPA627 seems to have dethroned my previous favorite AD8610 (Based on how it plays low cello notes in my perception while both are very detailed), i would think the AD8065 is a nice choice for you, based on what their reputation compared to the OPA627 and AD8610 is (low freq butt kicking is usually mentioned).
I will put them on order myself now. Since for my current set of headphones a little more on the low end would be nice.
The OPA627 often make me think 'spacious' even on my phonaks and have a nice warm tone to it, i find the XM5 to be completely black with the OPA627 compared to the AD8610 where i can hear some noise (don't want to call it hiss either) at full volume and winamp paused.

You could enjoy the XM5 with the OPA134s for now and let me waste my money on yet another opamp and see if it can dethrone the OPA627 as "well defined low end with clear detail" opamp or not. It's easy to find an opamp that is bass heavy, but vocals/details can suffer. (LM6171)

I think all the WhiteCats on that page have their compatible amp listed. (XM4 vs. XM5, which also means dual-channel vs. single channel, respectively) Where there's a picture of two whitecats, it's for the XM5 or any single channel amplifier.

Great review !
Now I have to purchase one ,probably next month

Cool !
How do you think the XM5 would fare would GS-1000 ?
Eventually, I will be saving up for these puppies

I think i'm going to hold my horses and listen to the opamps exclusively on the AD700, afterall, i bought an amp for full sized phones and not my easy to drive IEMs.
And the synergy of LM6171 with AD700 so far is far better than Phonaks on LM6171, i got to give time to each opamp on AD700.
Going to wait on AD8065 and will much more likely pick up LME49710 in between ($2.xx a piece in DIP-8). Promising chip, despite the price.

Hello, This is all very interesting! I am deciding between an ibasso d10 and this amp (well I am actually quite sure i will get the ibasso for my iriver but I would still like to try the xm5 for my laptop because of the nice customization options).
Can someone explain to me how this opamp+buffer system works? As far asI udnerstand it is best to have 2 opam sb ecause of the dual mono system, th eopamps amplify the sound and are important for how the sound signature is. The buffers give it more current. But then why canyou use opamps as buffers? I do not really understand this.. I mean you can use bufvfers as buffers, and i suppose you can tuse those as op amps but why can yfou use opamps as buffers....
Greetings, Anouk,

Well just got my XM5 today and this things sound great. Took a little more than a week to get from Canada to Atlanta.

I'm using the stock opamps and the BUF634 buffers.

Build quality is top notch, volume knob and all buttons are well put together precise and well designed.

The sound is great and just what I was wanting, very spacious detailed but warm and natural sounding.

I'm using the Bass and Treble boost with my Gen1 Zune on the acoustic setting and my Atrio M5's and am now approaching the sound quality of my 25,000 Lexicon\Anthony Gallo home system.

Obviously it is not quite to that point there but it certainly sound VERY good and is the best portable setup I have ever heard.

I'm getting all the details, all the bass and all the spacious warm sound I can handle and am not left for anything and no hiss what so ever even cranked up.

This was definitely the best portable amp for my tastes.

Congrats swanlee!


You know what really grinds my gears re the XM5?

Channel imbalance at lift off volume in low gain...really not that bad and only at sleepy time dB.

Anyone else experience this?

I can counter this bad vibe with my love for the knurled, over-sized volume knob...makes for quick & easy use...beats my Pico in this feature category!

Just checked and maybe the left channel is a tad louder at lower volumes on the knob but the volume is so low I'd never actually listen to it that low.

It's slight if it does exist and I probably would not have noticed it otherwise. Listening at low levels right now as I type this and I REALLY have to try hard to detect if there is a difference in channel loudness it definitely is not obvious.

Love the way this amp sounds though.

I believe it is the left channel being higher with my XM5 also(I should know this but would need to confirm). This imbalance is only at this very low volume. Once I move away from this low volume, the balance is dead on. I don't experience this with my Pico.

I'll ask you this since you're here...do you hear a slight bass boost when the crossfeed is engaged? I hear a slight bass boost, not anything near the +6 dB with the switch. I can only guess I hear a .5 dB boost...but it is there for me and I actually look for this small bass boost using the crossfeed...btw, I use crossfeed at the minimal setting...80 % of the time.

Question #2. have you used the DAC, if so how do you like?

I have heard a few comments about more than a few portable amps and even full stereo systems that tend to be slightly non balanced at very low levels so it's not at all un heard of.

I notice a very slight bass boost when Xfeed is enabled but I think that is because of what Xfeed does and not actually a true bass boost.

Take any stereo track and reduce the stereo field more towards the center and the bass will be more prominent.

I have not used it as a dac, I may try but I don't listen to music through my PC so it was really not a feature I was interested in, nice that it's there though.

I too did not need the DAC feature but I do use it as an alternate from my Pico DAC.

I can't disagree with your comments re the crossfeed. I once owned a HeadRoom MicroAmp which has crossfeed and I heard a very noticeable bass boost/added warmth when in use.

On the other hand, one other portable amp that I've owned also had the crossfeed option and I don't recall much bass boost effect, if any.

I do know that the XM5 has an "Active Variable CrossFeed" which is supposed to be different (better?) than competing designs. I believe that the volume is supposed to remain constant after the crossfeed is engaged...not sure on this. I do know that the claim is that it is the only variable crossfeed.

There's no doubt that this amp has a few cool tricks.

Passive indeed drops the volume, which makes A/B comparisons pretty much impossible, since you always fiddle with volume knob up and down, but i admit, if i engaged it on the XM4 and left the adjusted volume alone it sounded about as well as the XM5.
Active xfeed is supposed to add some delay to the signal instead of just mixing a fraction into either of the opposing channels. I can't say i notice it, but also, i did not have the XM4 and XM5 side by side to say for sure.

swanlee: you now have two choices, leave the opamp alone and go on listening to music, or picking up a couple different opamps and finding out if you could get a better synergy between amp and phones ;P

I for one am not done yet, got two more DIP-8 sets coming before i finally add the AD8065s from Practical Devices to the mix.

I'll have so many to choose from in the end, i could have a library of phones and find the perfect match in opamps ;P If i only had the budget for so many phones (LCD + Desktop comp are on chopping block already)

Either way, enjoy, it has made listening to music even more fun, and i agree analog volume control rocks.