indeed, the 901 works very well as a pre-amp. in fact, so many people were using it this way, that Grace added RCA outputs to the m902, to make it easier for people to use as a pre-amp. that's the only "downside" of the 901, that the only outputs are 1/4" jacks, so you need a custom cable for 1/4" > RCA connectors. a while back, I had leegeddy make me a nice custom silver cable that I've been using.
as linked in that playback phot thread, that's my 901 > grado rs-2 headphones. since that thread, I've gone through a couple of amps, and I now have the 901 matched with a pair of Channel Islands Audio VMB-1 monoblocks as my amp. it's fantastic, go for it.
- Jason