The Matrix M Stage is a great entry level amp. It has a slightly warm but detailed sound sig. Because of this, and its 4 gain settings, it pairs well with many different headphones. It drives the Pro 900s as much as I would want them to be driven. Over winter break, I flew home to Seattle, WA and only took my Ibasso D4 with me. The Ultrasone's sounded just great out of it, and I was happy with my temporary setup. Once I arrived back at my dorm and plugged the 900s into the Matrix, I realized how much it adds to the sound. The bass goes so much deeper and the soundstage is widened considerably. I also enjoy the Matrix because it acts as a switch between my Xbox and my computer, so when I want to stop listening to music and start playing some video games, I just flip the input switch on the front and I'm all set.
I like the Matrix so much that I won't upgrade for some time. In fact, I'll probably only upgrade once I buy a headphone like the D7000 or LCD-2 (or whatever else is out by then) and want to balance them, therefore needing a balanced setup. For now, and for quite a while into the future, the Matrix will be all I need in terms of headphone amplification. But since you want to know what amp I'd upgrade to NOW, I'd easily pick up the Meier Concerto, along with the StageDAC, if I had the money that is. Seems like an amazing setup.
Hope that helped.
Hey Jibbie, I'm considering upgrading to a Matrix M Stage amp, I currently have a Practical Devices XM4 which I bought just for the bass boost feature and it works pretty well, but I really could use a change. How is the bass with the M Stage? I'm hoping it would be tight and robust with plenty of depth/extension and impact.. With the XM4 it's like a night and day difference with the bass boost on with certain tracks, especially bass heavy dubstep and electronica, and I'd prefer to not have to rely on the boost all the time to get the effect I'm looking for as some songs (rock and industrial) sound too muddy and convoluted with it. If you were to upgrade from the M Stage, what amp would you decide on? I'm currently burning in my 2nd pair of Pro 900s, I had to get a replacement after I busted my first pair (had to leave for L.A. for 5 days and decided to burn in my phones during that time, but I put the volume on too loud and screwed up the drivers I guess, sound was only coming out of one channel.. fcking idiot I was). Fortunately Buyauthorized sent me an RMA and did a seamless exchange, highly recommended for sure. The 2nd pair didn't totally wow me like the 1st one did but it's slowly getting back there again and hopefully with the M Stage or something I'll be addicted once more :)