C123666, I used to think the tube cost was bad, but after researching and playing with the SF preamps, I found only two of the tubes made most of the difference compared to stock tubes. For example, the SF Line 2 and Line 1 only take 6 tubes each, and could achieve excellent sound with 2 NOS 7308's or 6022's at $100/pair, and 4 low noise new tubes at $20-30/pair. The Line 2 was rated a Stereophile Class A preamp using the stock Sovtek 6922's at $12 each. Buyers should also check the product's reputation for how hard the equipment is on tubes, since they last longer in some of the preamp designs. Partsconnexion says Pearl Tube Coolers can increase tube life (we shall see). To me, adding a tubed pre was worth it for the improved body and dimensionality in the sound of my system.