3. A detent-less volume control. It would be nice never to have to try balancing the knob on a high spot again.
People like different things, I suppose. I love the detent-ful volume and balance controls. They make it so easy to get repeatable settings--living in an apartment, I have different volume needs at different times of the day; I just count the clicks to get the volume I know I want in a simple, reliable, precise way. At the urging of a kind, local audio dealer, I auditioned some tube electronics in my home recently, and one of the irritations was the lack of click-stops in the volume control.
Not only did the tube gear not sound as good as my OmegaStar preamp/Insight power amp combination, but I realized the lack of features would drive me crazy (no balance control on one; no means to select left, right, or mixed mono, if there was a mono switch at all; very limited input options, no tone controls, no external processor loop, etc.). I'm very happy to have a full-featured preamplifier with great sound!