Kef LS50

Unlikely that an amp change will make a substantial or fundamental change. But if you're sensing something is missing consider acoustical treatment for your room. That can make a staggering improvement in your listening experience for a relatively small investment. 

In my living room, which has a lot of glass on 3 sides and no possibility of curtains, we used 2ft2 2" panels on the ceiling to try and tame things down. Even covering less than 50% of the area, we noticed a huge improvement in sound quality, as well as a quieter environment overall.  In the music room/theater, a full room package with bass traps was installed, and even casual visitors notice the sound quality is great. 

I used the Peachtree Nova 150 with a LS50 for about 3 years. If your room is small, then getting it acoustically treated will give you the biggest bang for the buck. I used GIK Accoustics for that ($700).

With some experimentation with the NOVA 150, I learned that the amp section of it is pretty good relative to the preamp and DAC. The preamp and DAC sections are lacking. Overall, the best thing about the NOVA 150 for me was the price. It is good for the price.

I tried an all-Benchmark system with the LS50, a LA4 preamp, DAC3B, and AHB2 amp ($6500 total and small form factor). This was so much better than the Nova 150. I may be using this setup with a future KEF Blade, that is how much I like it.

A CODA CSiB integrated was not as crystal clear as the BM stack, but it was also way better than the Nova 150. The CSiB lacks a DAC but a Topping D90SE at $800 is much better than the DAC in the NOVA 150.

A KRELL K-300i integrated with internal DAC is killer with the LS50 but not cheap. It has the first 90 watts in Class A. I love the new KRELL XD lineup. I sold the K-300i to buy the KRELL 175XD stereo amp. That was because I loved the sound of the K-300i.

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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.