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
Rogue Audio Tempest is a integrated Amp have you tried the phono input without phono pre amp it will run a MM 
"...Rogue Audio Tempest is a integrated Amp have you tried the phono input without phono pre amp it will run a MM..."

Good call, it's always worth trying, you might like one better than the other.  
From what I can see online (Rogue Owner's Manuals) the Tempest & Tempest II do not feature an internal phono circuit, just a line level input labeled as such?

While not familiar with the U-Turn tonearm specifically, cartridges do respond tonally to differences/adjustments of Vertical Tracking Force. On some systems, tracking force can vary dramatically when measured at distances other than actual record level.

Given the Ortofon 2M Red recommends a VTF of 1.8 grams + or - .2 grams, you may try lightening a bit. Treat the counterweight like an old-school single knob electronic tone control where less weight accentuates the highs and conversely, more weight emphasizes bass. Adjust to where it sounds right on your system.