Well a week or so after my earlier reply to this post, I took the plunge and purchased the Sigma 160i with MC phono and balanced input.
Break-in was about 220 hours (including the 50 hours it gets before leaving the VACtory). It has about 300 hours on it now. I put a pair of NOS Mullard 12AX7's in the phono section yesterday. It is hands down as good as my Art Audio Vinyl Reference (both using Lundahl transformers).
The balanced input gives more transparency and dynamics than the RCA inputs when used with a studio master tape recorder (Otari MTR-15).
The bass is solid-state deep and taught and the power and neutrality are superb. It is plugged directly into a 20 amp dedicated circuit with a Shunyata Anaconda Helix power cord. I use the Hi-Fi Tuning fuses in all my gear and bought the 5A Supreme fuse for the 160i.
I hesitated long and hard in going the integrated route because I was very, very happy with the music made by the aforementioned Vinyl Reference with Joule Electra LA-150 MkII preamp and Genesis M60 monoblocks. I have absolutely No Regrets musically, financially, or aesthetically!
The VAC integrated allowed me to get rid of three HRS isolation bases, three expensive power cords, and two pairs of reference interconnects - an investment about equal to the separate components. My music room is a whole lot less cluttered-looking to boot.
For anyone looking for true reference level amplification and who has speakers that can be driven with 85 tube watts per channel, the VAC Sigma 160i may well put an end to your search. I give it the highest possible recommendation.
Footnote: The first post in this thread by Barrelchief mentions the "Alpha Integrated" as the predecessor to the 160i. While true, be aware that the 160i is not in any way a derivative of the Alpha Integrated design. The latter was a merging of circuits already developed and used in the Phi preamp and Phi amps. The Sigma 160i was designed from scratch on a blank sheet of paper. This no doubt accounts for its almost magical musical reproductive abilities. While it lacks the "eye candy" and "audio jewelery" qualities of the venerable Phi Beta 110i, it is in every other way a most worthy successor.
