Your opinions on what speakers to go with?

You need to think about pro speakers - your current speakers are already quite powerful but you are having the typical compression and "ringing" issues from consumer designs (rigid light weight cones small VC's and small motors). You probably listen louder than most people and need an internally damped (doped fabric or paper/pup) traditional type design.

Check out ATC, PMC, Meyer, and JBL studio monitors and you will surely find something you like. Big horns such as large Tannoys or traditional corner loaded Klipsch's (old but they are famous for good reason) are also an option that will suit your taste for loud and dynamic sound (like the real live performance).

Be wary of typical low cost towers with multiple woofers - it looks impressive but the woofers soon compress - better a simple two way like Meyer X-10 with two expensive high performance pro drivers than a multitude of cheap low cost woofers. What you see is not always what you get. What looks impressive is often just that - looks.

I pretty much disagree with Shadorne. Nice system! I owned 150s. It should be in Ultralinear and you should be using KT 88s. Also I found tube bias needed to be adjusted regularly. You could have some dead (or near dead) tubes.

Power cords, interconnects, and speaker cables all make a difference. I really like Morrow Audio MAP2 power cords, Either PS Audio Transcendent silver interconnects or DH Labs Revelation. Get XLR if the preamp has XLR I/Os, if not replace it with a differentially balanced preamp! Ditto the Consonance. The Raysonic 165 is killer and the balanced tube outs are so good you can eliminate the preamp all together! Clear Day solid core silver shotgun speaker cables. If after doing this you still have speaker issues look at Usher, Triangle, Reference 3A...

Of course, if this is something you are only experiencing recently then Tweak could be quite correct - you may have a tube issue. Another challenge could be microphonics when you play loud. Pink Floyd's studio have their tubes in an entirely separate room to avoid the microphonic problems at higher volume levels. I seriously doubt if cables/interconnects can cure a problem that only appears at higher volumes.

My advice was based on your stated interest in trance/dance genre and "like to listen loud". Check out this setup from a guy who mixes for Kaskade and other DJ's for club music.