One more vote for Manley. I bought a pair of TSM-Mmi last spring to mate with a Stingray II and I'm extremely happy with the sound. The Manley puts out around 20w in triode or 40w in ultraliner. In my very large room, ultralinear is the way to go, as triode struggles just a bit at both frequency extremes. The output impedance is 5 ohms, which is just right for the Merlins' 6 ohm load.
Another nice feature of the Stingray II is its RCA sub out, which makes it very easy to integrate a subwoofer. I use a small, sealed-cab Von Schweikert set at 50 Hz and its seamless.
You could also pick up Mahi monoblocks, which are almost identical to the Stingray II but you'd need a preamp. Either way, the Manley/Merlin combo is a proven winner. Add a sub, a decent source, and quality cabling and you have a system that hits way above its weight.