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.

Just for the general info pool: The four rectifier diodes are right next to the transformer and would take all of 20 minutes(if one were really challenged as far as dexterity) to change out, at a cost of less than $16.00(if IXYS soft recovery FREDs were used). An upgraded power cable should be considered a "must", regardless of what preamp is discussed(figure around $200.00), unless the unit comes with one. YES- The coupling caps(especially) will make a dramatic difference in sound, but finding the ones that suit one's tastes can be harder(and less predictable in the unit/system) than rolling NOS tubes. There again NOS tubes should be considered a "must"(if maximum musical enjoyment is the goal), regardless of the gear discussed. AND the ones you don't like can be sold at just slightly less than what you've paid(you'll know if they're keepers in the first 10hrs, which won't affect their measurements in the least). IOW: Most of what he would spend on his LS-7, would be spent on any other tubed unit he might purchase, in the effort to obtain enhanced music reproduction.