pre amp suggestions

A few months ago a friend and I adjusted the impedance and it sounded best at the factory setting I think. However it sounded best at it's current setting, then we tried adjusting the gain and removed the module but there wasn't any adjustment controls and that's when I contacted Rowland and was told that the gain could not be adjusted on this particular series. I guess that I would have to start looking around for another power amp e.g the Rowland 8t, krell evo 402 or some other s s amps. Feel free to make suggestions. Currently the system sounds ok but to me and some of my friends it's a bit dark and I believe it's from the Rowland.

Before suggesting any amp alternatives, here are a couple more questions for due diligence:

1. Have you checked the status of your pre tubes? Is there the possibility that they are depleted? Here is what Lam says about them:

"NOTE: we recommend replacing 6C19P and both 12AX3 tubes about once a year
to maintain the best performance of the preamp"

2. Are you using balanced ICs? Both L2 and JRDG M5 seem to provide XLR connectors. M5 appears to be symmetrically balanced and should yield higher performance in a balanced configuration.

What power cords are you using on your system?

Bery old thread but i cant help but notice not 1 person thought of reccomending the OP insert an Active gain control in the loop that would have added +12 db which is a massive jump in gain, its how i solved the same problem with my Rowland 501 amps,a decent quality gain control can be bought well under $100.