I've been lurking around here for a while -- and my thanks to all of you for giving me a good sense of direction.
I decided to go from a good-but-not-exalted headphone rig to something a lot better. After years of using (and enjoying) Sennheiser HD 600s, I moved up to HD 800s; I've had those for a while now. But I was aware that I wasn't extracting the maximum out of them, with a Mac Pro feeding into a Benchmark DAC1 USB and its headphone output. I think the DAC1 is a first-class product, but I'm not sure it's ideal for Sennheiser 800s. Overall the Senns sounded a bit clinical with the DAC1, but they improved quite a bit through the headphone jack of my Arcam integrated amplifier. I noticed on the forums here that my sense of the HD 800 being fussy about amplification was shared by other folks.
So I've upped the ante considerably, much to the detriment of my bank account but to the delight of my ears. Now the 800s are driven by a Luxman P-1u amplifier, itself fed by a Bryston BDA-1 DAC, preceded by a Musical Fidelity V-Link and then into my Mac Pro's USB port. I'm moving between iTunes and Amarra MINI for playback; I prefer the Amarra sound, but its interface remains a bit rough around the edges. My music library is almost entirely in Apple Lossless format, with a sprinkling of AIFF files, and a huddled clutch of mp3s mostly resulting from downloads.
That's the setup in the picture above. Both the Luxman and Bryston have had enough time to play in, and the results are nothing less than astonishing. I auditioned the Luxman amp at the dealer with my HD800s, and they lit up like Christmas trees. There's a fine synergy between the HD800s and the Luxman P-1u. Maybe that partnership can be duplicated with another amplifier, but I couldn't be happier with this one. It's a lot of audio real estate on my desk, but I listen mostly with headphones in my home office, as opposed via speakers in the living room.
I've been finding that I prefer to send an unmodified digital stream through the V-Link -- well, except for 16-bit to 24-bit in the case of 44.1 files -- and then to let the Bryston handle upsampling. At least to date my ears like that better than in-computer upsampling. Sort of like rendering unto Caesar that which is Caesar's; i.e., use the computer to manage, catalog, and send the data stream on its way, let the Bryston transform that data into an analog signal, then hand the finished analog signal over to the Luxman to do what it does so well. I imagine a line of sous-chefs each contributing to an entrée that is subsequently brought to my table by my faithful waiter, Herr Sennheiser.