Thank you, Stevecham and Soix. OK, so here's my confession: I only recently acquired 4BST, and am not using it yet, but trying to get a good preamp match. The Dali 400's are a recent aquistion as well, so I'm still getting familiar with them. So far I think they are fantastic across the entire frequency range, but when listening to one recording, an older jazz recording from the 60's, the sax sounded a bit harsh and edgy. However that may well be his tone. As I've listened to other recordings, I get no harsness, but crystaline clarity in the highs (and rock solid, clean bass as well). I'm currently using a Rotel 1052 Receiver (100 wpc). Fine for what it is, but not a match for the Bryston and Dali's. My interest in a tube preamp was as a result of my ABing a Cary tube vs. a Cary SS pre at a showroom. The tube sounded more open, transparent, airy and fluid to me and I liked that. The dealer said, that's what you get with tubes somewhere in the chain. (Of course he was trying to sell me something.) Others (here) have suggested tubes, such as AR pres might be a good blend. Now, that said, although I have a good ear and know music, I am not savy elecronically, and when you guys start talking about matching output impedences, I get nervous. E.g., the AR LS16 has output of 600ohms balanced and 300 ohms SE. So would that match with the 4BST 20K and 50K? The Cary SLP 03 has output impedence of 500 on XLR and RCA's. (Would it work on the Bryston?) Moreover, most I can't find the output impedence listed for most preamps. Do I need to worry about this? Should I just play it safe and go with a Bryston, and put aside my tube dreams? Also do I need to put the Speaker impedence (4ohms) into this equation, or it that only and issue for Amp choice, vs. preamp, as I'd assumed. Help.