Very small room systems and synergy

I have considered an amp change but really like the size, price, and convenience of the NuPrime. Any suggestions on that subject?

How do you have your speakers positioned? 

You say you're not getting enough bass and you're using speakers that go down to 47hz 6db down. Personally I agree on the subject of metal dome tweeters give me a soft dome any day. But what you need are either bigger speakers with better bass response or a subwoofer.

My room is the same size and have been into this since 2003. I agree maybe a larger 8" two way might be better in regards to frequency response. High efficiency with a tube amp would be even better. I've owned alot of more expensive speakers, but right now I'm having great results the Paradigm Atom v3 (bought used locally for $20.00). These are paired with a $100.00 appj 2013 tube amp and Sangean hdt20. This is the best "complete" system I've had in this small room. I think the source and tubes made the most difference, but the small speakers open up at low volumes and are forgiving in the right way.

I forgot to mention that I've read some prefer omni directional speakers like the Ohm Walsh Tall in small rooms. This has something to do with the indirect sound can use the room to better than conventional speakers. I've never heard these though and they seem kind of pricey for what you get. I honestly think you are hearing an "unbalanced" sound. Rather than metal dome irritating you more than likely the sound is just unbalanced in some ways and the highs are what you notice.