Beyerdynamic DT880 600 ohm:
Truly beautiful headphones, excellent build quality, materials and fit & finish. Feels and looks very expensive in person, much more than Sennheiser HD650 or AKG Q701. They're also more comfortable than either, with very soft ear pads, very thick and soft headband, virtually no clamping force and lightweight construction which makes them really disappear from your head when wearing them.
Sound is very neutral, very smooth, nothing pops out, it just sounds like it has a ruler flat frequency response, but with somewhat increased feeling of clarity. Some reviews might give you a wrong perception about these headphones, and you might read negative things about these headphones which aren't true. I was fooled as well and kept postponing my purchase for years, until I actually tried them on my own. Some claim they have weak bass, they sound thin, they have recessed vocals, are very bright up the top, have metallic sound, etc, which is all wrong in my opinion. I guess they aren't the most exciting headphones to listen to, which is never the case with neutral headphones anyway.
Something about the "weak bass". Actually the bass is more present than in the HD650's, I'm talking about REAL bass, from 20 to 80hz. HD650's have a mid-bass hump that makes them feel more punchy, but in reality all it does is muddy up the sound a bit in certain songs. Bass on DT880's is bottomless, with better extension than HD650's or Q701's, very full, very controlled and textured, with lots of nuance. Makes the HD650's bass seem boomy in comparison, and Q701's bass a bit thin and too quick, kinda like hitting a wooden table with your knuckles type of punch. Although in terms of quantity, DT880's might not have the most bass (the amount is close to perfect for me), I feel the DT880's have the best bass QUALITY of any headphone anywhere near their price range. It's not all about quantity... the texture, detail, control and smoothness of bass is what matters the most.
Mids are less forward compared to Q701's, but nothing that is noticeable while listening to music, and its because Q701 mids are forward. Vocals and instruments still sound clear and vibrant, although not quite as full as on the Q701's or HD650's, but if I listen to DT880's and then switch to either of those two, I feel they sound colored.
Highs are smooth, very detailed, extended, sparkly, and give a nice sense of that crystalline quality to the entire sound of the headphones. But they're never harsh, in fact, the treble doesn't bother me any more than on the HD650's. Nothing else to say about the highs, they're just...faultless.
Soundstage performance I feel depends highly on material played. I don't atually believe in headphone soundstage per se. In my opinion its more about the actual frequency response of the headphone that determines the sound stage effect that we hear. After all, most of the soundstage is "built in" into the recording, it just depends on how the headphone reproduces the sound. What I do know though, is that the DT880's feel very opened in sound. Very airy, despite their "semi-open" design. "Soundstage" is not quite as wide as with the Q701, more similar to HD650's, but it has more depth than either, and a better central presence than Q701's.
Isolation is virtually non-existent, although the sound is a bit muffled with the headphone on.
In general, these are VERY good headphones. Can I say they're better than HD650's or Q701's which are their main competitors for years? Not really, it would be like saying a BMW 7 series is better than Mercedes S class and Audi A8. You can't say that, because they're all excellent in their way, and in overall score would be pretty equal. But the fact is, DT880 has no real faults in my opinion, IF you want a neutral headphone. They do nothing wrong. If I were to nit pick with HD650's or Q701's, I could find a fault or two, but with DT880's I could not, because they do what they're supposed to do so well. They have a clear direction in which they're going. They know they're neutral headphones than need to sound exactly as the recording, and they do that.
All I'm gonna say is its a great amplifier for the DT880. PLENTY of power, transparent sound. All I need. They run DT880's to ear bleeding levels at 60% of volume, with lots of headroom to spare. It has built in dual Burr Brown 24/192 DACs, so you don't need a separate DAC or a soundcard if you use this amp.
Overall, I found this speaker amp to be a better headphone amp than many much more expensive dedicated headphone amps. In general, integrated amps and receivers have excellent headphone outputs these days, if you own one, you don't need to waste money on headphone amps.
I compared the A-5VL side by side to Asus Xonar Essence One, Teac UD-H01 and Cambridge Audio DACMagic Plus, and it EASILY beat them all in terms of power, and was as good in terms of sound, its a dedicated audio component after all...