Power 1, 2,3 I am not impressed by these. I am not impressed by their higher powered SFS-80 and SFS-160. Mine had better treble than almost all other tube amps I used, but the woolly bass is not too good, and cannot be ameliorated by tube rolling, hence its Archilles' heel. SFS-50 is the earliest one, and I have used it, but I think the next one, SFS-40, using E元4, is the best sounding of the whole lot. Using RCA connection somehow loses dynamic. They should be run in balanced mode for best results. Line 1, 2, 3 Based on my extended hearing of friends' Line2/Power2, and Power 3, I'd think these are OK, but not great. But its price is not bad for a balanced tube preamp, and worth a try! SFL-2 Haven't seriously heard this 2-box flagship with balanced features, reputed to be clinical sounding. ARC wins hand-over in every department, particularly dynamics, yielding ground perhaps only in imaging. It sounds reasonably good with a good tube and has very good imaging, but if you compare it to an ARC hybrid preamp that uses also just 1 tube, like LS-1/SP9 (which I did), there is no comparison. Beware IC failure is common, though it's not difficult to repair. But it is the transistor part of this hybrid preamp that is troublesome. It can be configured to use 1x 6DJ8 or 1x 12AT7. SFL-1 This is the first one, and has numerous incarnations and special edition. I have heard the Processor 3 in my home and I personally think it is not as good as the earlier SFD-2. For similar reason I would avoid the transport. Transport and Processor 3 These are later ones. But the problem of this player, and the SFT-1 transport, lies in the unreliable laser mechanism, Philips CDM12 (.4 I believe). SFT-1 and SFCD-1 The SFCD-1 is actually a very good player, since it uses their own DAC. Ultrajitterbug and Transdac I have owned both before but IMHO they are not as good as similar products from the contemporary Audio Alchemy or Monarchy Audio. It does not sound nearly as good as the SFD-2. SFD-1 This is a cheaper version that uses only 1 chip and does not have balanced features. Just recently, in a friend's place, it completely slaughtered the DAC section of his Acuustic Arts CDP (whose transport section is no good either all those over-rated reviews!). But either one will still show a clean pair of heels to much more expensive, especially modern DACs. I suspect, contrary to popular opinion, the cheaper MkI is better sounding. I have owned before a MkI before it went bust, and still own a MkII. Later beefed up MkII does, but there are also minor changes and cosmetic variations within its long production, which I shall not go into. SFD-2 This is the earlier flagship which uses 2 chips and has balanced outputs. I believe this is one of the best DAC chips ever. I put this first because I think in this area they excel, partly because of the era during which they produce products was the era of the excellent (and expensive) Ultranalogue 20-bit D20400A chip. I have used and heard a lot of their products. Information on old SF products can be found here. They went under later but the AV subsidiary Anthem is still around. Back in the early 90's, Sonic Frontiers was all the rage.

Sonic frontiers sfs 50