upgrade from Peachtree Deco 65 to Nova 150s (with Reference 3a MM de Capo-i speakers)?

Is there something that you feel you are missing and hence the change or is this more of the "audiophile I have to change because I have not changed anything in awhile" feeling? No shame in that as we all have done it, are doing it or will do it soon. The de Capo speakers are pretty efficient if I recall correctly so I am assuming the 65 refers to the current watts per channel? More power is usually not a bad thing but again, your speakers are pretty efficient.
How about this? Are the deals being offered including a free trial? If so, try the 150 and see what you think. If you like it better, great! If not, all you are out is some shipping and a few hours to repack the 150 and ship it back. I can honestly say that for me, there are times that I have made a change even though I was not really all that serious and it was more of a spur of the moment thing, and those often have giving me the most pleasure as opposed to over-thinking something.
I hope that helps somewhat. I cannot recommend the Nova 150 directly but even if I had heard it I would always strongly suggest that you try it in your home with your gear as there is so much to this "system synergy" thing. What is cool in my home might very well be poop in your home.
Good luck!

Hi, thank you very much for your reply, very thoughtful.  Honestly, I've been flat out with work and family for most of the last 5 years, am now coming up for air, and wonder, in terms of audio, how much has changed in 5 years and what I might be missing. The speakers are great and, yes, very efficient, and I imagine the Decco is the (relatively) weak link. I didn't have much money when I bought it (got a good deal used) and thought I might want to upgrade at some point.   Some say it works best as a preamp and that the speakers are designed ideally for a tube amp. But now that I've thought about my system, I'm also using the stock power and USB cords and basic Monoprice speaker cables, so there might be a whole lot I can do now that I have a little time.  Just upgrading to Audiorvana made a real difference.

No free trial deal with the Nova 150 but I did write Peachtree directly about these questions. (I've been very happy with their service.)  Thank you all for any advice you might have!