Thinking about buying a different tube preamp...

Here's what I did. I re-connected the Jolida with the pvc removed and there is a little hiss, not real bad, but audible. Then I put the Modwright back in with the pvc removed as well. There is a hiss that is quite audible from my sitting position, around 10 to 11 feet away.
I contacted Dan Wright and he stated that the earlier models had more tube rush than the later models. I'm unsure as to which this one is, earlier or later.
The Classe monoblocks have a sensitivity of 1 volt in for the rated output. 29.02 dB gain and an input impedance of 75 Kohms.
The Jolida has an output impedance of 600 ohms, the Modwright 300 ohms.
I'm guessing the difference I'm hearing is just the type of the tubes being used in different configurations. The Jolida uses two 12AT7 tubes for power and two 12AX7's for the pre-amp. The Modwright uses a 5AR4/GZ34 rectifier tube and two 6SN7 signal tubes.

OK- my surmise was correct- you have a lot of gain with that amp. If you want the Modwight to work you will have to hand-pick the 6SN7s for low noise. This should not be that challenging- we use 6SN7s in all of our line stages and can get them to be nice and quiet on speakers that are much more efficient than yours!

I would also listen to the character of each preamp and see which you prefer. Generally speaking I find that I like 6SN7-based circuits better as they are usually smoother without lacking detail. But that is not always the case so you will want to play them and see which you like other than the noise.

If the Modwright comes out on top then you might want to consider some boutique tubes for it- hand picked by Andy at Vintage Tube Services or maybe Sophia or TJ Music tubes; Kevin at Upscale is a good source too. However you do it the tubes should be returnable if there is a problem.

Have fun! but don't drive yourself nuts- different tubes sound different and some people go right down the rabbit hole with this and trust me on this one, its not worth it! You want to solve the problem you have and spend the money left over that you didn't spend on 50 other types of tubes just getting more tunes to play :)

Thanks for all of your information, Atmasphere. I like the Modwright fine and will do some experimenting with different tubes. When I purchased, it came with 2 sets of tubes. The first set were Sophia's, and one was terribly noisy. Still have to test them to see if one's bad.
I'll pick up some others to compare. Something to look forward to!

Black Treasure CV181s (6sn7 equivalents) sound great in the LS100; guessing Psvanes would as well and Dan does recommend the Sophia's on his LS100 webpage

You should be aware that just because a tube is new does not mean it will be quiet or low microphonics. Tubes in premium gear almost always have to be hand-picked, despite what you pay for them.

So you got one Sophia that was noisy- send it back and see if the next one is better.