After my positive experience with the Matrix X-Sabre and having known about the M-Stage being a popular inexpensive amp for HD800s, I began to recommend it to a few people in this thread and elsewhere who were trying to build a amp/DAC combo for HD800s for $1000 or less. I recommended the $600 Concero and the $260 M-Stage. A week or so later I decided to get one for myself so that I wasn't just recommending blindly. I got it Thursday and got it plugged in and playing on Friday and it's been going nearly 24 hours a day since then, only taking breaks when I was comparing with the BHA-1. I got the M-Stage with USB DAC for an extra $30 because why the hell not, and initially listened through the built in DAC.
At first I was pleasantly surprised at the performance, it wasn't super detailed, but it seemed clean with a wide though thin sound. I honestly didn't expect much from this DAC since it was so cheap, and after listening for a while longer I began encountering some showstopping harshness on some tracks. I would say this DAC could be a decent stand in DAC if you had to be without, but you'd want to keep the volume below live. The sound was dynamic and punchy, but not overly clear or well textured. The harshness became regular as I began to recognize it everywhere, but most of the time it was ignored easily enough.
Having given a few hours to the onboard DAC, I was ready to move up to a real DAC and hooked up the X-Sabre to the M-Stage and gave it a listen. The difference was as expected given the $1070 price difference in the DACs, but I was also relieved to know most of the negative bits about the M-Stage was from the DAC, and not the amp. With the X-Sabre the M-Stage opened right up with very good clarity and without any of the previous harshness. After listening for a few hours and noting that the performance was really special, I knew the next step was to compare to the BHA-1. I was reasonably sure before making the switch that I knew what I was going to hear in the difference, but after having listened to the built in DAC, the X-Sabre -> M-Stage combo was worryingly good.
With the X-Sabre and BHA-1 in balanced mode and balanced connection to the HD800s, I listened to a dozen or so specific tracks I thought would highlight differences easiest between the M-Stage and BHA-1. Despite the balanced connection and the price difference, the performance was really not as much better as one might expect. I was right, though, in what I did find. As I described in my post above about mid-fi vs high end, the main aspects people focus on were better, but not a lot better. The big strides for the BHA-1 were in the refinement areas, textures, layering and the sort. There is certainly a distinct difference in performance between these 2 amps, but in the core aspects, it is remarkably close.
I am glad to say my faith in the reviews of the M-Stage/HD800 combo was not unfounded. I will certainly recommend this combo to anyone wanting to step into high end with the headphone first. It is the most important part, by far, but not spending a truckload on the amp right away takes careful consideration. The M-Stage is a great stepping stone for the HD800s, such that you could even make a DAC upgrade before worrying about the amp. Listening to the X-Sabre -> M-Stage -> HD800, is truly a high end experience, though just barely. There is plenty of room to improve, but it is mostly in the refinement areas that take good to magical.