Modern technolgy for starter 24/96 DAC

Hi Folks!

It's my first message here. I'm looking to slightly improve my Windows-based audio system to stick in an external DAC. I'm budget-constrained to spend around $300 right now.

My current setup:

* Windows/XT, mostly MP3 files with various compression
* External $50 audio card Creative SoundBlaster X-Fi Surround 5.1. It has both optical SPDIF 24/96 and analog outputs
* Analog from Blaster is directly fed into Arcam Delta 290 Power Amp (it's former integrated amp converted into power). It's very good old power amp, has no volume and control buttons, all turned off
* KEF Coda

All that is actually sounding pretty well, though not great. I would like to slowly upgrade this stuff, and for various reasons that are too long to explain I want to just put a DAC there:

* The optical from SoundBlater will be fed into DAC, analog out will go to Arcam

My question is:

People say that the technology is growing exponentially. The output from my cheap SPDIF card is 24 bit/96 kHz. I think it is sampling properly, I don't hear any defects. I can buy here at Audiogon:

1. Old 20/44 DAC that used to cost $1000+ 10 years ago
2. Almost new 24/96 that used to cost $400+ 2 years ago

In both cases it will cost me around $300. Is it possible that cheap modern DACs are actually sounding better?