M-Audio DUO as DAC

[metako]

I have only recently started playing 44/98 music files from my WIN 7 laptop via Foobar KS drivers to a M-Audio DUO USB preamp which is about 10 years old. To my ears the sound is quite good except bass is quite woolly and doesn't go deep-the rest of the spectrum sounds better than my CD player.

My question is whether it is possible to improve the sound of this DAC and whether it is worthwhile given the following specs (some of which I don't really understand):

USB 1.0 only
max res 44bit /98Khz
isochronous streaming (which I take it means no asynchronous streaming)
JRC 5532 op amps
TAS 1020A USB streamer controller
NE555-33M oscillator (clock?)
M-TEK D4101DA (what is this?)
NSK 6.000 (ditto?)

The data sheet for the TAS1020A states:
"A direct memory access (DMA) controller with two channels is provided for streaming the USB isochronous data
packets to/from the codec port interface. Each DMA channel can support one USB isochronous endpoint.
An on-chip phase lock loop (PLL) and adaptive clock generator (ACG) provide support for the USB synchronization
modes, which include asynchronous, synchronous and adaptive."

does this mean it can't do asynchronous USB streaming-this is a major drawback isn't it? Is it worth playing with different op amps or should I start with a more modern budget DAC?

[metako]

It also has
AK4103 (A/D converter?)
L7915CV/L7815CV/L7805CV regulators.

[metako]

Another way of asking this is: if I replace the op amps with say OPA 627's (on brown dogs) will I be missing out on very much in terms of sound quality given the other components?