Interestingly, the M504’s were rated for 4Ω in the EU market but not the North American one? Probably because they didn’t meet the US Standards for heat.
But as the Ohm Walsh 2000 are rated at 6Ω so you should be fine as is.
Now, if you wanted to try tubes, I’d suggest a pair of monoblocks.
I have both solid state and tube monoblocks. My speakers are Martin Logan Spires which can go down to 1Ω (and are known to be very demanding on amps).
My s/s amps are Soundcraftsmen PM860 that put out 900 W at 4Ω. I can entertain the neighbourhood with the volume at 3/10.
My tube amps are Golden Tube Audio SE-40 which I’ve upgraded all caps and resistors. They put out 75 W. While they lack the sheer punch of the PM860’s, they drive the ML’s quite nicely and are much more musical.
Or, find another Crown PS-400 and run them as monoblocks. That would give you 530 W at 8Ω.
But as the Ohm Walsh 2000 are rated at 6Ω so you should be fine as is.
Now, if you wanted to try tubes, I’d suggest a pair of monoblocks.
I have both solid state and tube monoblocks. My speakers are Martin Logan Spires which can go down to 1Ω (and are known to be very demanding on amps).
My s/s amps are Soundcraftsmen PM860 that put out 900 W at 4Ω. I can entertain the neighbourhood with the volume at 3/10.
My tube amps are Golden Tube Audio SE-40 which I’ve upgraded all caps and resistors. They put out 75 W. While they lack the sheer punch of the PM860’s, they drive the ML’s quite nicely and are much more musical.
Or, find another Crown PS-400 and run them as monoblocks. That would give you 530 W at 8Ω.