I've got the 55TXi, and just recently converted all of my CDs to MP3s. So last week I hooked up my notebook via the USB to the 55TXi, and I was very pleased with the results. But this was just a couple of hours of casual listening, and was more enamored with having my entire collection available as a jukebox! Way cool.
Anyhow, I'm planning on sitting down and listening to comparisons btw the original CDs and the MP3s (I used LAME), and see if I'm truly happy with the final product. But it appeared to work fairly well, and there were no immediately obvious audio defects.
Didn't listen to any Windows sounds or anything else.
Take care,
Rich
