another rookie question - preamp or or power amp

i think it is the best idea... And at the lowest price...

It can be possible to even integrate a tube pre-amplifier in these mono amp i think...

The Fosi headphone amplifier i bought for peanuts price , the Fosi sk01 + 3 tone controls is a steal...

It is not chinese junk ... I use a tube low cost pre-amp with it the Douk P2 at peanuts cost too which i use also for my near field active speakers ... Very good sound ...

It seems audio china is no more junk only ...

For a bit higher price than what i paid  ( 60 bucks ) you could have a very good tubes pre-amplifier under 200 bucks ...

I would go pre out from your IA, into two Fosi ZA3’s run in Mono mode. Get the 48V, 5A power supplies. The two will run you about $300, and I believe you will be majorly delighted with the power and sound quality. These 3255 chip amps are amazing, and I believe they will be the next big thing in terms of amplification.

OR for the same $ our intrepid OP could get a GAS Son of Ampzilla and get a nice robust linear power supply vs. SMPS … 48 v or no…

Just my opinion…

The size of the power amp you need has to do with the efficiency of your loudspeakers, how large the room is, how loudly you want to play your music, and how much power your loudspeakers can safely take.

If you can use your existing integrated amp as a preamp, then get a power amp first.  The amp you quote, the Parasound 2125 power amp, is NOT available at $400, so why even talk about it?  There are a number of good value amps at $400 or less on US Audiomart.  Why not go there to look for one?

Parasound 2125 power amp, is NOT available at $400

thanks @tomic601 Holiday spirit indeed :)