300B SET or EL34 SET

Look at a 300B + 845 or 805 tubes amp. 

You can have the 300B sweet midrange and glorious 3D image with great bass and dynamics (if you dont match it with extremely difficult to drive speakers). 

I have a Line Magnetic LM-508IA integrated with 300B and 48W per channel and it blew away a VERY nice class D amp I still have (in a box), even in fields where the class D amp should be better like dinamics and detail. Not to mention the much sweeter middle frequencies.

My speakers are 90 Db sensitive and 6 ohm of impedance, with minimum of 4 ohm and the LM508 drives them with incredible authority. 

I've had a cheaper EL34 push pull integrated, but the LM508 is completely  on another league. Its not cheap, but an incredible amp. 

Something else to mention. 

At low volume levels I believe it could be more important that your speakers are good at that volume. Not all are, some need medium volume levels to start sounding alive.

My very best listening setions are at night, with low volume levels (everyone is sleeping). The AC current is so clean that I cant believe the sound of my system. Incredibly engaging. 

@plga
Which speakers do you have?
My ATC SCM19 doesn't come alive before the volume is to high for me. That's why they are in the closet now. 

Check out Audio Mirror 45watt SET mono amps. 6C33C tube based. I have these and really like them. In my system they brought a whole new level of performance and refinement. You can roll input tubes to customize the sound and the power tubes are inexpensive. Vlad was great to deal with. 

Hello @simna
My speakers are the Q Acoustics Concept 500 floorstanders.
I've been told by a couple of dealers who sell them that they think the C500 are the best you can get at that price range and even for considerably more money. I know its about personal taste, but both dealers sell a LOT of brands and they have tried and sell many different speakers from every price range. 

I would check reviews on the Line Magnetic LM-518IA, the smaller brother of the LM-508IA (wich I have).

Some reviewers like Tim Smith from Wall of Sound and Herb Reichert from Stereophile, not to mention some forums on the web, rave about this 300B/845 integrated amp (the LM-518). Tim made it his reference amp, over many he had auditioned.

On the other hand, everyone who has heard both amps, the LM-518IA and LM-508, prefered the latest for being more dynamic. Thats why I bought it and its one incredible integrated that you can later also use it as power amp adding a good preamp and taking it to another level.

I have to admit, 300B and 845/805 tubes are considerably more expensive than EL34, but they also sound better.