Been out of the game a little while so bear with me please. I drove the last car i had a system in through a intersection and totaled it

Audiocontrol/all CDT speakers/zx600ti were sold off and that pioneer hu was nothing to write home about 6 years ago or so. Ive still got my pair of 4 ohm alchemy's and they look to have survived storage without any issues. The zx350v2 is most likely dead as i was careless and moved the box that it was in to my non heated garage and left it next to a window for about 18 months. IDK if its survived or not but its got some nasty surface rust on the case. We'll assume its dead, the right channel was gett'n weak before i smashed up the car anyway.
Now im gett'n close to finishing my Mustang for cruise'n season but i'll need some tunes.
The plan as it stands now is a pioneer deh-p880prs or a deh-p860mp(if i can still find one), one of my alchemy's in a .9cu sealed box. I may hunt myself up another audiocontrol three.1 but those newer pioneer hu's might be good enough. I have a set of old infinity refrence 605cs comps that i purchased for one of my past gf's cars but never installed. They should be good enough to get me going. If i find i really must have rear fill coaxials off the hu should suffice and they are cheap anway. Just need to decide on amps. I was think'n something like a xenon 100.4. Front channels on the infinity comps and the rear channels bridged to the single alchemy@4 ohms. Then if i found down the road i really must have that second sub i can throw a xenon 400.1 on the 2 alch's. I will be running a set higher end seperates for the frontstage eventualy, i had my eye on CDT eurosports and dynaudio seperates before i got out of the car stereo game.
How do these RSD/xenon amps compare to the old MS/ZX/Ti series amps? Hard to compare to some of the best amps ever made. The low prices on these new pg amps has me a little concerned. I think im going to keep my eye out for a zx/ti 500.4 for a little while since im used to em but wanted to get some input on these xenon's/RSD's and how they would fit in my current set up and how well they will grow with what i want to do.
thanks