Windows Media Player

I would be more concerned with teh sound card I was using than the plybck softwr

I wouldn't under estimate the importance of the pc configuration and software. The final result is very cumulative IMO.

The Media Jukebox is free and is as good as mediamonkey...i love it.

Interesting. THis is from the CMP^2 sorceforge site that Nikki posted. Some tips for better USB DAC performance. Not exactly on topic, sorry.

1. Connect the DAC to a back-panel socket, not to the motherboard’s on-board USB headers;
2. Provide the DAC with its own power supply – do not power it off the motherboard;
3. Use an after-market USB cable. (These can make a measureable difference.)
4. Disconnect all other USB devices when playing music;
5. Disable USB 2.0 in BIOS (enable USB 1 only: USB 2.0 can be re-enabled when needed);
6. Disable USB power management. Select Control Panel > System > Hardware > Device Manager > Universal Serial Bus Controllers and expand (click on +). Right-click each Root Hub in turn and deselect [Power Management] > Allow the computer to turn off this device to save power;
7. Disable unused hubs. Select every Root Hub as above and find the DAC’s (right-click, Properties > Power). Disable the rest (perhaps leaving one or two for housekeeping): right-click and select Disable (not Uninstall as XP will reinstall the hub at the next restart);
8. Remove ‘non-present’ devices. XP notes devices hitherto connected to the USB. To clear the record, launch a command prompt, type set devmgr_show_nonpresent_devices=1 [Enter], then devmgmt.msc [Enter]. Leave the window open. In Device Manager, click View > Show hidden devices and uninstall all USB devices (both ‘ghost’ and current) and reboot with the DAC on. The step may have no effect but can resolve obscure driver issues;
9. Check the DAC has a unique IRQ (see Step 6 above);
10. Check PCI latency timing. The values determine how many clock cycles elapse between a device taking and relinquishing control of the PCI bus. Some manufacturers set defaults too high so that their devices deny prompt access to others. The shareware ‘PCI Latency Tool’ can view and possibly adjust them (depends on mobo chipset): if some are unduly high, try reducing them to 64 or 48. Note that crudely setting the DAC high and all else low is counter-productive – the idea is to enable smooth access by preventing any device from bus hogging;

It is not claimed that the above steps will tranform the quality of an entry-level DAC but, taken together, they tend to make for more reliable performance and usually for better sound as well.

Paulsax,
All the computer optimizations that cics describes will make a significant improvement for USB DACs.

Reducing DPC latency, CPU freq, Vcore and using single channel memory made the greatest impact for me in refinement and detail.