I have used a VAC Sigma 160i with the Harbeth Super HL5+ and it was a very solid match. I've also used Naim, Sugden and other ss amps with Harbeth with limited success. None had the magic that the VAC did. A year ago, I attended AXPONA and visited the Vinnie Rossi room where he was using his gear with the 40.2s. It was the best match I've ever heard with Harbeth. I am currently running the LIO with P3's and I couldn't be happier. This may be interesting:
http://aumacoustics.com/vinnie_rossi/
http://aumacoustics.com/vinnie_rossi/