Here's my experience with Harbeth and VAC:
- Harbeth M-40.1's with Renaissance 30/30 MKIII had the best midrange I have ever experienced, but the bass was a bit loose and wooly. Female vocals and jazz are outstanding with this amp, but classical with complex passages could have benefited from more power.
- Harbeth M-40.1's with Renaissance 70/70 Signature had a nice warm relatively balanced sound... highly detailed, but very smooth and easy to listen too. Great with female vocals, jazz, acoustic and classical, but not so much with rock.
- Harbeth M-40.1's with Phi 200 (current setup) is more neutral than the Renaissance amps, lacking some of the magical midrange from the Ren's 300B's, but the bass is very solid/robust and the highs are notably more extended than the older Renaissance series amps. I get the best sound using the 2-4 ohm tap. Sounds good with all kinds of music, including rock and classical with complex passages.
- Harbeth SHL5's with Renaissance 70/70 Signature was a good combo... good dynamics, not overly warm and quite transparent. This was the only amp I tried on the SHL5's. I found I missed the bass that the 40.1's provided, so I sold them and purchased my second pair of 40.1's. I found the SHL5's to be too strident/detailed for my taste.