What to upgrade/do next?

I concur with those that believe the TT to be the weak link. A ProJect Debut carbon with cartridge can be had for ~`$400 leaving $$ left for phono stage. There is also Rega or Music Hall versions at that price point. Check out Needle Doctor or Music Direct online. They also have many phono stages for sale. NAD makes one that provides the USB function if that is desired. Good luck and let us know how you proceed.

If I run my turntable on "line" through the NAD I can definitely get it up loud enough. If I switch it to phono, it still comes through the speakers, but incredibly quiet.

Setting the switch to "line" routes the signal from the cartridge through a built-in phono preamp, while setting it to "phono" will bypass that phono preamp, and output the signal straight from the cartridge. The "phono" position will be used with an external phono preamp.

I do agree with a TT upgrade, however the first step should be that external phono preamp, as this will be needed when using an upgraded TT.

Thanks. So any suggestions for a good and affordable phono preamp? That will bump things up in quality a bit before I get a new TT, right? Anything that would go nicely with my nad?

NAD sells a range of phono pre-amps that are generally well received. I'd look there first.

I agree with getting the phono stage 1st. Given your budget of $1000 max for both items, I would set aside $500 for the TT to include cartridge. Keep in mind that the cartridges that come with a turntable are good compliments at the selling point, however, one of the best upgrades that can be made for vinyl is to upgrade the cartridge. The beauty is this can be done at a later date.

When considering a phono stage it is important that it is compatible with the cartridge used regarding output and loading. I own a Lounge Audio LCR MK-II. I believe they now sale online for ~$225. It provides 40dB Gain. I believe it loads at 47kohm, 100mFd so will suit many MM or HOMC cartridges. I use it with a Bluepoint No.2. You may want to look into the Lounge online. My decision was based on budget and wanting a phono stage that provided 40 dB gain as the Bluepoint only outputs 2.5mV. I believe the NADs only provide 36dB. Had the 3ppi USB one and preferred the Lounge. I once own the Jolida JD9, which retailed at $450. This was one of best sub $500 phono stages. A hybrid tube model with great flexibility regarding gain and loading. There is now a newer version selling for ~$600. Check out Needledoctor and Music Direct to compare many of the options. There are many choices, consider your needs regarding cartridge output and loading. Take your time to insure you best satisfy your needs. I am sure others having more experience will chime in. I