Audio Research LS-7 LS7 upgrades suggestions

The easiest path is to install some NOS CCa's or, at least 7308/E188CC tubes. Depending on your taste in presentation, you might try Siemens/Telefunken(very transparent and extended in both directions, w/o bloat or glare), Mullard/Brimar(warm, "tubey", British flavor) or Amperex Holland/Valvo/Phillips(middle of the road, and beautiful, especially the "pinched waist"). All will provide better imaging and sound stage depth than anything currently manufactured. Replace the fuse with a Hi-fi Tuning piece. Major improvements in overall presentation and dynamics can be had by installing an IEC inlet(Furutech and Oyaide make some nice ones), and upgraded powercord(ie: Synergistic Research X2 AC Master Coupler). Another step providing more natural sound overall would be to replace the rectifier diodes with CREE Schottkys, HEXFREDs, or soft recovery FREDs from IXYS. Perform the steps individually, so you can appreciate the impact each has on the sound of your system.

Rodman is right on. Replacing RCA jacks may help too.
Get some estimates first. I suspect that it may pay to sell this and buy an already updated unit. From what I know, some of the other models are better? 6C or 8's?

You may end up spending $700 and never be able to get it back out of the unit. However, it is still a really nice piece.

Replace the Rel-cap coupling capacitors (the yellow ones).

Thank you all for the responses.