Some insight from Tyll about the M8
"It appears that when Michael Goodman decided to build a new portable headphone amp he pulled out a fresh sheet of paper and rethought the whole concept. He wasn't afraid of getting input from others either, and much of the dialog in this Head-Fi thread informed his creativity. I spent a good bit of time listening to this amp at The Home Entertainment Show while at CES and I found myself quite impressed.
Though I only got the chance to listen to the amp using unfamiliar music from a laptop in the booth, I found the HiFi-M8 clean, articulate, and full-bodied. But the thing that really caught my attention were the very well thought out rear panel switches. I worry that some novice users will wonder what they're for, but they were a sight to behold for this old headphone geek's eyes.
Using my 22 Ohm impedance Sennheiser Momentum headphones I could readily hear the change in driver control and damping between the 1 and 11 Ohm output impedance settings. I suspect I'd use the amp primarily in the lowest output impedance setting, but some headphone enthusiasts swear by higher output impedances for some cans.
A three position gain switch is provided offering up to 30dB gain in the highest setting, and is noise-free enough in the low-gain setting for efficient custom IEMs.
The amp also has both bass and treble boost settings. I'm looking forward to measuring the amp to identify exactly what frequencies these filter are set for, but I can tell you that I found the bass boost switch to provide a very tasty bump, low enough in frequency not to get in the way of a balanced transition between the bass and mids. In other words, it didn't make things sound murky.
The treble boost is a surprisingly welcome addition. As you may know I'm not a fan of too much treble response on headphones, but I have noticed that very often headphones lack response in the highest octave between 10kHz and 20kHz. Evidently Michael has also noticed this problem, and has included a two position treble boost switch for these frequencies to improve the sense of "air" on headphones lacking in this area. In the case of both the treble and bass boost switches, I found the settings nicely judicious and not overdone.
Though I really can't comment on the quality of the DAC section on quick listen, it is asynchronous USB and capable of up to 24/192 bit rates, and can accept inputs from both computer USB and iDevices. The amp has both balanced and unbalanced headphone outputs.
Edited by zeinharis - 1/27/13 at 6:29am