SET amplifier (for AvantGarde Duo's-original) recommendations

Hello all,
I inherited the above speaker and I have been really enjoying them.  I also have a pair of Thiel 3.7s- paired with pass labs xa60.5's (and it works!) which I also love albeit they are very different animals from the DUO's as you can imagine.

Right now I am focusing on the Duo's and have used them both with Pass Labs and a Mastersound Compact 845- both are great but there is something about the DUO's driven by this 845 SET that is magical.   The problem is that the 845 was dropped and developed a hum.  A technician went through it and managed to reduce the hum but it is still there and it bugs me- I am not sure if one of the transformers itself may have been damaged and that isn't really repairable at reasonable cost, though I will speak to Mastersound to hear their thoughts. I should add that the amp used to be dead quiet and generally Masetrsound makes superb amps- and are renown for their transformers.

So I am now starting to think about alternatives solutions- I would like to either stick to a SET of comparable quality (that is known to be relatively quiet with efficient speakers)- maybe a 300b type just for a change, or even an OTL.

There's a lot of stuff out there at the moment, take the Line Magnetics that are floating around (but would they compare to Mastersound in terms of build quality etc?) and I was hoping to get some insights on what you think would work well.  I have read a lot of reviews and while helpful at times I feel they are almost always positive and a little too generic  when comparing similar products.  I'd like to stick to a $5k or so budget (therefore I would look for something used).