So I bought a brand new 668 last night from radio shack...
If you bought your PRO-668 directly from Radio Shack I assume you either paid the full regular retail price of $500 or $375 if it was "on sale." Either way I think you would have been much better off purchasing a brand-new Whistler-branded handheld instead for a few reasons. Seeing that you just purchased your PRO-668, I'm sure you could return it to Radio Shack if you are so inclined after reading the following:
1. Radio Shack offers no factory repair service or parts for their scanners. If it breaks during the warranty period they are "supposed to" exchange it for a new working unit but after the warranty ends Radio Shack will no longer help you AT ALL. Whistler, on the other hand, offers both in- and out-of-warranty factory repair service with a flat-rate $120 charge to repair Whistler scanners that are out-of-warranty.
2. The PRO-668 has no official DMR upgrade available. While it is true that you can "unofficially" load Whistler CPU firmware version 3.8 into your PRO-668 in order to get DMR reception, you are currently stuck at 3.8 while the Whistler-brand scanners are up to CPU firmware version 4.5.
3. The PRO-668 has no NXDN receive capability which the Whistler TRX-1 handheld has and the TRX-1 (which includes a $30-value case in the box) can be purchased brand-new for less than the $500 regular price of the PRO-668 at Radio Shack.
Here are the 3 similar Whistler models as compared to the PRO-668:
WS1080 is essentially the same scanner as the PRO-668 but it has "official" DMR receive capability from Whistler and is still being supported by Whistler with software and firmware updates.
WS1088 is the same scanner as the WS1080 but with the addition of a keypad.
TRX-1 adds NXDN capability, is reported to have an improved front-end compared to the WS1080/WS1088 and includes a case with the scanner that is not included with the WS1080/WS1088 (case sold separately by Whistler for $30).