Plug amp and other gear into separate outlets ?

If you have a good electrician, either works well.

Fremer is right, in that, given the varying ages of homes, and varying quality of grounding, that plugging everything into 1 outlet is less likely to cause problems, but these problems are really obvious. You’ll know in seconds!

Amps.... this depends a little more, on your amp, and listening style. If you play loud, or use particularly hot running amps, then they will draw more current, and be a little more likely to cause the incoming voltage to sage in proportion to the current being drawn. If you have monster Krell class A, fully balanced amps, yeah, separate outlets will help keep your system sounding more solid. For your average Joe amp, like a Parasound A21 or A23 or Class D, not so much.

OF course, the ONLY thing that matters here is sound quality. If you can’t hear a diff, pick which ever is most convenient.

I have a separate outlet run from my box dedicated for the amp and had rest on another, switched over and don't think I can tell a difference. I am running a pretty powerful amp, Mark Levinson 532h at 300 watts per channel and do like to play loud at times for heavier rock like LZ, Pink Floyd , Hendrix, etc. I think I'll just keep amp on its own circuit. My wiring in basement is fairly new. 
Thanks for your response. 

@initm - a lot of this type of issue can be attributed directly to the power cords and power conditioner or power distribution panel being used and the quality of the outlet itself.

e.g. I have my amp connected directly to the wall outlet, but my components are connected to a power distribution box which plugs into the second port of the same wall outlet.

However - that distribution box is wired in such a way that "electrically", it appears to be just an extension of the power outlet it is plugged into - i.e. the individual outlets are not wired in parallel

The better the power cord quality and outlet quality the less effect current draw of the amp will have on the overall system perofrmance.

In a perfect world you would have one outlet per component and there would not be any ground issues. But we all live in a house/apartment where this is not possible, so a more common sense approach is often required

There are excellent power distribution boxes out there from Furutech and PS Audio and a whole host of power cables. Signal Cable power cords are pretty good and will not break the bank

My favorite outlet is an Pass and Seymour MRI grade outlet from Take Five Audio - they won’t break the bank and clamp the plug very well

If you are into DIY take a look at this power cable...
http://image99.net/blog/files/category-002ahelix-power-cable.html

I have this cable throughout my system and it has proved to perform better than some very expensive competition

Hope that helps - Steve

My experience is that by plugging the whole shebang into a single outlet, hum and noise are the lowest possible in my home.

Williewonka, I have a PS Audio medical grade outlet with Audioquest power cord on amp and Shunyata Venom3 on receiver, so upgraded power cords though not the top range cords. I have Furman power conditioner for all except the amp as I've been told it can constrict power to amp. Thanks for feedback. 
It's a fun and interesting ( and expensive ) hobby!! You can tell a difference, major difference with better components, tweaks and acoustics. If anyone hasn't tried Tidal for HiRes streaming I'd suggest, it sounds fantastic, better than my flac files. 

@initm - your source is correct in that many power conditioners will constrict the amp.

However, the Furutech e-TP609 NCF power distributor should provide more details than the Furman.
http://www.furutech.com/2017/11/24/15943/

I replaced my Panamax power conditioner with a distributor of my own design that is along the same lines as the Furutech and found the difference in details quite noticeable.

You seem to have the power side covered quite nicely, so the only other thing that I highly recommend is the gZero3 or gZero6 interconnects.

Here are my reviews of those two IC’s...
http://image99.net/blog/files/7f98bfec4730a5b7984e5fcb36b813d4-52.html
http://image99.net/blog/files/b1d68fc60965c695cb9f7656d931fc88-55.html

They are a step up from many other cables on the market and reproduce those exceptionally fine details other cables are unable to convey

Again, if DIY is your thing take a look at these IC’s
http://image99.net/blog/files/category-002ahelix-interconnect-cable.html

Will a new DAC improve things? - from what I have read it is possible.

However, my investigations into cables over the past 5-6 years has taught me that today’s components are capable of providing a performance that is far beyond what their more modest price points would suggest.

The Node 2 is one such component. It will be with me for a long time to come :-)

That’s about it from me - good luck with you quest :-)