Flat speaker sound/preamp the culprit?/external EQ needed?


Hi, I have a Rogue Audio tube amp, which I love, a U-Turn turntable and an NAD phono preamp. Here's my issue: on many recordings the bass can really drown out the rest of the record. In general things sound muddy. When I plug my iPhone directly into the amp, I dont have this problem. So I think the premp is the culprit. (It has no EQ controls.) Can someone recommend a reasonably priced solution to this? An external EQ? Something else? (Someone recommended a Schiit Loki.) Many thanks in advance!
ineedhelpwithcables
Do you have the MC/MM switch set correctly? plugged into the correct MC/MM connection? A high output MC would go into MM side (I think). 
So this did it! I switched the preamp to MM and the muddiness went away. I looked up Uturn's website and all their cartridges are MM. 

Thank you all!

I would still be interested in preamp recommendations where you can adjust the bass, if such things exist.  Would the Schiit Loki do that? 
Glad we could help out. You don't need tone controls you need a better cartridge.