I own a VAC Sigma 160i and I can tell you this Integrated is simply gorgeous. I can imagine that the VAC Sigma 170i will be even more refined. I got an used VAC Sigma 160i from a fellow Audiogoner and I have trouble lighting up my McIntosh C2600+ ARC VT100 Mk2 combo in preference to the VAC. It is simply wonderful to listen to and be forewarned, it is tube rollers paradise. I have some NOS Brimar CV4003’s and Mullards($$) in that amp along with Golden Lion output tubes and boy does it sound gorgeous. You will not be dissapointed...I am playing through a Vandersteen 3A Signature speakers...and the Vandy’s are hardly exotic in the high end world... it is pure magic to my ears.
I own three other Integrads including a Primaluna Dialogue Premium HP, Anthem STR, Krell KAV 400xi and while the Primaluna and the Anthem are both highly rated amps(and much lower price point), they do not shine a candle next to the VAC. It's not even close.