Power Conditioning on the Cheap

Regarding wire gauge, the gauge should be paired with amps.  Your electrician will know.  If your wire is already at 14 gauge for 15amps, and if you want to save some money and stick to that wire. Or you can upgrade to 20amps if you think you are getting electronics that need to run on 20amps.  https://www.familyhandyman.com/list/cable-and-wire-basics/#:~:text=The%20most%20common%20sizes%20you,%2Dgauge%20and%2012%2Dgauge.

Also, think about changing the outlet to a hospital-grade/studier outlet.  Or splurge for an extra $30 for one of these.  

I think the question of gauge depends on what you are doing. My guys ran 4 gauge from the output of a very large isolation transformer to a secondary panel adjacent to the listening room, and from there, ran 10 gauge from the panel to the outlets, which are 20 amp hospital grade Hubbells- made to spec for Albert Porter (and no longer available, bargain that they were). I think it is less about audiophile "approved" than good practices. The guy I alway call on is @Jea48. Simply for his practical knowledge of Code +. 

The top grade furutech power outlet. Then after that furutech top with of the line AC and IEC ends on your power cords. Start at the wall one set and keep going until you decide it's time to relax for awhile to pl

From your text it sounds you already decided you want to buy a Power Conditioner. My questions is ... is there something wrong / missing with your current sound that pointed you in this direction as being the solution?

It could be that maybe if you change another component, or improve room acoustics, experiment with speaker placement or port (if they have them) tuning, improvements can be made that have more impact for the same or less investment than adding a power conditioner, which will probably only make a subtle audible difference, if any at all.

Since you say you have this budget cap, other solutions could be more money efficient. But of course the high tech looks and ’estheatics’ of a power conditioner added to your rig may give a nice feeling and may be worth something too.

The Furman PST-8, for the money, is very good. You mentioned the PST-8D, be advised that that model is dedicated to digital sources only. I’m not certain if you are aware, Garth Powell is the designer of the Furman PST-8. He used to work at Furman. He is the same guy that designed the Audioquest Niagara 1000 and 1200, as well as the more expensive models.

I will agree that it is advisable to run a dedicated circuit to your hifi. It can be done cheaply (if you are proficient in electrical work) by running a 12/2 romex (yellow) from a 20 amp breaker to a high quality receptacle (audioquest Edison for example). Then you will also need to buy some high quality power chords to take full advantage of your new found better quality power.