I don't think there is a yes/no answer until you a/b stuff in your own system. I have gone back and fourth with my Sony XA7ES's variable output. Currently I favor the use of a vk-5i tube preamp with my vt100m2 tube amplifier. I lose a little resolution, but there is just a smoothness/soundstage to the presentation that I prefer. That is using all balanced quattro-fil i/c's which are much higher resolution than other i/c's I have used.
Sometimes a system will increase in resolution when using a preamp. When I went from cd->pass labs amps to cd->pass labs pre->pass labs amps, I heard an obvious increase in resolution and quietness. With my older, entry level hi-end stuff, I preferred direct output. Once I started buying $4000+ preamps (for MUCH less on audiogon of course), I found I preferred using a preamp.
Sometimes a system will increase in resolution when using a preamp. When I went from cd->pass labs amps to cd->pass labs pre->pass labs amps, I heard an obvious increase in resolution and quietness. With my older, entry level hi-end stuff, I preferred direct output. Once I started buying $4000+ preamps (for MUCH less on audiogon of course), I found I preferred using a preamp.