I have the Proac 140 mkII speakers, not the same league but somehow similar specs.
I also had a Yamaha 2000 integrated which I also used for a while as a power amp with my tube pre.
The Yamaha 2000 is very similar in specs with the L505u.
My room is somehow bigger.
I replaced the 2000 with a McCormack DNA 225. And it was a difference of day and night. And mainly in the drive of the speakers. Much more and better controlled bass without booming, fuller sound in lower levels and better SQ generally.
Probably the McCormack is a better amp overall but I think that the main factor is that the Proac wanted more and better power.
I want to clarify that I do no hear loud, I live in a flat.
But the better ability of the McCormac to drive the Proac gave better sound at all levels. The 2000 was more than enough loud even at the 1/3 of the maximum volume, but didn't have the same convenience.
My suggestion is to try to demo an amp of 150-250 W at 8 Ohm that goes near the double at 4 Ohm and has good quality sound.
I don't think that an A class of 30 W per channel can drive adequately normal floor standing speakers (not tube oriented) .
I don't know about tube power amps.
I am sure that the D40 can give you much better sound.
I also had a Yamaha 2000 integrated which I also used for a while as a power amp with my tube pre.
The Yamaha 2000 is very similar in specs with the L505u.
My room is somehow bigger.
I replaced the 2000 with a McCormack DNA 225. And it was a difference of day and night. And mainly in the drive of the speakers. Much more and better controlled bass without booming, fuller sound in lower levels and better SQ generally.
Probably the McCormack is a better amp overall but I think that the main factor is that the Proac wanted more and better power.
I want to clarify that I do no hear loud, I live in a flat.
But the better ability of the McCormac to drive the Proac gave better sound at all levels. The 2000 was more than enough loud even at the 1/3 of the maximum volume, but didn't have the same convenience.
My suggestion is to try to demo an amp of 150-250 W at 8 Ohm that goes near the double at 4 Ohm and has good quality sound.
I don't think that an A class of 30 W per channel can drive adequately normal floor standing speakers (not tube oriented) .
I don't know about tube power amps.
I am sure that the D40 can give you much better sound.