I have had Quad S2 speakers and now Quad Z4. At first listen they don't sound very exciting as they are smooth with midrange bodied sound and were never designed to over impress. But once you start living with them they are very good speakers with great details and amazing imaging abilities. I have also found these speakers are very finicky with placement but once placed correctly and after getting used to ribbon tweeters, they reward with very sweet and non-fatiguing sound. They are also very resolving and will show any weaknesses in the chain easily including poorly recorded sources. Demo them if possible but don't expect a very impressive sound at the first listen. You really have to live with them. You will like them if you like non-fatiguing sound. They have a certain tone which is very sweet but not very live and natural' if you care about that. I believe they will sound very amazing with a tube amp, though I have never tried. I think it's hard to beat the price/performance of quad s series.