Having now had this headphone amp for 4 months or so, I thought I'd write a quick review. Just to emphasise these are only what I found, your own findings may be totally different. Within the last year I have had a Hugo and Naim V1 both of which were good but did not give me the exact sound that I wanted. The Naim, was just too hot in the treble and would get fatiguing, the Hugo was a little boring, on both occasions I used PS1000 headphones.
I then found a pair of Stax 009 and a 007t Kimik amplifier, fed by a Rega Isis valve CD player, they only stayed with me for a few weeks, I just found the set up unexciting and uninvolving. I then went away on holiday and whilst sitting around a pool in the sun, had read about the MHA100, wow, that looks stunning! I had always liked the look of Mcintosh gear, but was put off by the price. Several monhs later, by chance I saw a MHA100 advertised that was only 6 weeks old, the owner was part exchanging it for an MXA, as he really wanted a speaker set up. I had to have it, this was either going to answer tick all the boxes or it would be sold on quickly, but at the price, I really had nothing to lose.
Well a few days later it turned up at work, I couldn't get it out of the box quick enough, it was the first piece of Mcintosh gear that I had seen, so far so good, I liked the look of it. After what seemed the slowest day ever, I got it home and plugged it in, the looks now became a thing of beauty, I was hoping it was going to sound as good as it looked. After spending an age trying to get my iPhone connected via USB/camera connection kit, I settled for a unbalanced connection via phono inputs, using the phone Dac, just to listen to some music. Ok, but not brilliant, as to be expected really, I was "on the fence".
Fast forward 24 hours and I was connecting an iMac via USB. Wow, that's more like it, this thing was sounding good into the PS1000, but perhaps a tad too much bass! That weekend I tried a optical lead in replacement of the USB, this was starting to sound as though it could be a keeper. The bass was reduced and the spatial soundstage grew, the best way I can describe it is, with USB you are in the front row of the audience, with a nice wide soundstage and the music coming from in front of you. However with optical you are actually on stage with them, instruments surround you, and you can keep track of any instrument you choose. The whole sound gels together and presents itself so naturally, smoothly but with exciting edge.
The icing on the cake to this great piece of equipment, was that I recently took a flyer on my second pair of HD800s (having sold the first pair a few years back) and the pairing is really quite magical. If you own a pair and want to hear them at their best, I would strongly recommend getting a listen to this amp!!
At long last I found a solution to my headphone needs.