Inexpensive but good sounding power supply (and hard drive) for PC audio?

Hello! I am about to replace my hard disk and power supply in my audio PC due to aging and I'm wondering if there's room for improvement (but without investing significant money) compared to what I'm currently using. Please advise me:

1. What power supply to buy? What to look for if I'm interested in sound quality on a ~ 150Euro budget: brand (I'm reading good things about Seasonic and Corsair), power (600W? 750W?), bronze vs. gold and so on?I know some people are raving about dedicated servers running on LPS and so on but I cannot afford the expense atm.

2. Can I expect a better or at least not worse sound after replacing the hard drive with a SSD? Any specific recommendation for a SSD?

My system consists of:

- a generic PC running Windows 10, used for streaming Tidal and Qobuz. It sports a WD Blue hard disk (no SSD), a cheap, generic power supply that costs about 10-15 Euro, I3-6100 processor @ 3.7GhZ, Asus B150M-K D3 motherboard and a Clearer Audio power cord (about 250 Euro) that, to my surprise, brought a significant improvement;

- much more expensive, "audiophile" audio components: Aurender DDC, Accuphase player / DAC and amplifier, Martin Logan hybrid electrostats

The reason for this disproportion between the cheap computer and expensive audio gear is that I've tried several "improvements" to the computer part and in the end I didn't prefer the result:

- a dedicated Lumin U1 Mini streamer. My PC was better to my ears (fuller, less sterile sounding)

- a Matrix PCI-USB card. Even when fed by an expensive Ferrum power supply, it was not a straight upgrade and overall I think I preferred the PC

- more expensive cables (power, USB, Ethernet) or DDC (Audio GD) that sounded worse

- a few Cisco switches, a better (Sotm) power supply for my router - sidegrades or downgrades

Thank you!