I am still with the Quest but I did have the opportunity to try the Riviera APL01SE which was excellent. I am constantly amazed at how well the Rei pair up with so many different systems.
I recommend Aries Cerat preamp. I also own Clarisys and they need warmer sounding gear along, Aries cerat perfectly fits the bill. I also have an experience with Westmister lab, when I ah Tannoy Westminster Royal it really sounded great toghether not so with Clarisys. As I said Clarisys need warmer and fuller sound. Some may disagree, just my point of view.
Zappy Daddy, I really like the Ares Cerat gear and their preamp. That said, Ron Resnick and I have had a very different experience with Clarysis (Piccolo, Studio Plus, and Auditorium) in that the Westminster (Rei and Quest) pairing was superb with all of them. Clarysis speakers have undergone various iterations with their crossover, and their tonality has evolved with each iteration, which makes absolutes hard.
We wrote earlier that we like pairing tube pre-amplifiers with the Reis. Brands such as Riviera, Trafomatic, Aires Cerat, ARC, VAC, etc, make excellent pairings with the Reis, if, within their own varied tube voicing, one desires a warmer, in some cases less dynamic sound than the Quest provides.
Interestingly, this week, one of my best customers, who owns the Westminster pairing as his primary electronics, also purchased a Trafomatic mono tube amplifier for those occasions he wants to enjoy a more romantic sound provided by the amplifiers' SV-111 single-ended tubes. The bottom line is that personal preferences dictate, as with all things high-end audio.
PS Hear This and our small cadre of retail partners offer in-home demonstrations of our products, and in many cases can provide a top tube pre-amplifier for comparison to the Quest in your system. Anyone interested, simply PM me and we will make it happen!