Best speakers to use with Mahi Mahi amps

Along with the Mahi Mahi I use a Woo Audio WA2 preamp, RAM modified Shanling CD T100 and a REL Strata III subwoofer.

I listen mostly to Progressive Rock, Jazz, Acoustic Blues and Bluegrass. Budget for speakers is $5K or less

I wouldn't claim that these are the "best speakers" to use with the Mahi's, but with mine I am running a pair of Merlin TSM-mmi's and they make wonderful music together. Bobby P of Merlin is a tube lover at heart and while my Merlins sounded fine when I ran them with a Bel Canto S-300 "Class D" amp, they really started to sing with the Manleys. Hope this helps.
I second Merlin speakers with Manley gears. 2005, I ran my TSM-MX with a Stingray, and later a pair of Manley Snappers with them. Then, moved up to a pair of VSM-MX.
Do a search engine, you'll find many pos.threads about Merlin/Stingray.
Good luck.
Not to be rude, but you've got this backwards. Speakers vary far more in sound than amps do, so speakers are the most important component to choose first. Nonetheless, given the low power of the Mahi amps I'd choose some very efficient speakers.

Have you considered a pair of used Legacy Focus? You'll get at least 94db out of the first couple of watts at one meter, and the sound is pretty good too. The Focus is great on jazz and rock.
". Nonetheless, given the low power of the Mahi amps I'd choose some very efficient speakers."

I used to think this was true but it's not always the case. I've heard Harbeth's with some relatively low powered amps at my local shop and I was impressed. Valves to boot.

R Burke. How do you listen to your music? I would imagine not blistering loud or you wouldn't own the Mahi. Based on your music preference, you might actually be a good candidate for Harbeth's. I would research the Harbeth Compact 7's and Super 5's. I have your same taste in music and I was extremely impressed. They'll work well with your sub too, in the right setting. I would also check out those Merlin's based on what others have said.
I run Merlin TSM-Mmi with a Stingray II, which is basically the integrated amp version of the Mahis. Along with a small Von Shweikert sub, this combo fills a large room with great sound. The Stingray's 40 watts in ultralinear mode are more than enough, while its 20 watts in triode are not quite enough in my room. The Merlins are a tube-friendly 6-ohm load and the Manley amps are optimized for 5 ohms, so the match is good in that regard.
Don't be fooled by the watt rating of Manley amplifiers.
Living Voice IBXR2's sounded great with these amps. They liked the long wall and needed a little room.

A pair of vintage 15" or 12" Dual Concentric Gold Tannoys in a custom cabinet were also a good match.
Sorry to sound like a broken record but "Best" is in the eye/ear of the beholder. There is no definitive "best" anything, it's all subjective. When you ask a question like this, the answers will always be what folks think is "best" to them in their system. Just my opinion so take it or leave it. Good luck.
Merlin (with RC network tweak for tube friendliness) , Triangle, Zu, Tannoy.
Irvrobinson is 100% right - choose the Merlin VSMs (speakers) first, then find the amp to drive them, the Mahis would be a very good choice.