Kef LS50

I know my comment does not really pertain to your thread, but how does the peach tree and musical Fidelity products sound? Are they entry level amps? Does Hegel out perform these products? Looking for amp for my Sonus Faber Sonetto V's.

There is any number of amplifiers that would serve as an upgrade to your Peachtree. It really depends on your budget.

This is in context of the fact that the LS50s are extremely revealing speakers. I have hear them on the end of tens of thousands of (€/ $) of high end equipment and they were not found wanting.

I also owned a Nova150 before moving on to separate components.  I agree that with the same loudspeakers, you may not hear a very significant difference in SQ just from a new integrated amp.  Tweaking the speaker positions, listening position, and room acoustics are all likely to make bigger differences. Furthermore, in terms of form factor and control features, the Nova 150 actually is quite good.  

But if the upgrade bug is really biting you, you might consider moving up the Peachtree line to the Nova 300, or better yet, to their Gan400 amp and PreDac. Through a Peachtree dealer, you may be able to get a fairly generous trade-in on the Nova 150. Some of the pricier Peachtree products use more advanced DAC chips and may also be quieter, compared to the Nova 150. Some of them also offer balanced XLR inputs/outputs. Or, for the price of the Gan400 + PreDac, a dealer may be able to show you alternatives you'd prefer. Maybe Anthem STR or one of the NAD integrated amps that offer built-in room correction and front-panel LCD touch screens. 

there are lots of better integrateds, though they do cost more...

We could better advise if we knew your budget and more info about your source components.