I suspect that the weak link is the ION TT
I started out with an ION iTT-USB for LP conversions and was so disappointed that I soon junked it. Although the electronics (the onboard soundcard and USB services) seemed very good it was let down by its extremely lightweight plastic platter (which led to wow & flutter) and a very cheap low-grade cartridge. Instead I use my existing hi-fi deck and I have a phono-preamp (ART DJ-Pre11) and an external USB soundcard (Edirol UA-1Ex).
You stated earlier that the sound is good on your existing deck so I would suggest using that and investing in say the ARTcessories USB Phono plus http://artproaudio.com/artcessories/turntable_preamps/product/usb_phono_plus-ps/ which is a combined pre-amp annd USB sound card in the one box (I would probably have bought that at the time had it been available). You may be able to sell the ION on eBay or wherever to cover some of the cost.
The LP recordings I make are converted to AAC 256 and sound truly excellent when played on my iPod either through my hi-fi amp/speakers or on my Sennheiser earphones (but not on the silly little earbuds that Apple supplies).
Tip: have a look at Brian Davies’ excellent ClickRepair software, it costs a little but is well worth it IMHO. The results it produces are a little shy of magical and far superior to the current click removal in Audacity - see this sticky thread: Click/pop removal - ClickRepair software
WC