Miketuason - If you don't feel like replacing all the tubes, the most important place for the 5751's would be to replace the 2 12AX7's in the phono stage. Theoretically, they'd make the biggest difference there as the decrease in noise would be most helpful there.
If you've got the amp still under warranty, it might be a good idea to just watch out for good buys on some of the 5751 or 12AX7's that have been discussed here. If you go out hunting for specific tubes (and want them now), you'll pay a lot. But just keep an eye out for all of the good ones and try to snipe them at great bargains.
If you've got the amp still under warranty, it might be a good idea to just watch out for good buys on some of the 5751 or 12AX7's that have been discussed here. If you go out hunting for specific tubes (and want them now), you'll pay a lot. But just keep an eye out for all of the good ones and try to snipe them at great bargains.