If you know what to listen for, and thrill to the sound of live music in a real venue: nothing beats tubes. Any equipment(tube or SS) takes time to sound it's best. Taking the time to burn in gear, and taste various tubes, is an act of love for some of us. Skydivers(I) have a saying: "We that dance are considered crazy by those that can't hear the music." Harley riders(I) have another: "If I have to explain- You wouldn't understand." Oil-filled caps will usually have somewhat of a fuller, rounder midrange(ala Mullard tubes, for instance- which some like), than would most film/foil caps(polypropylene/copper foil probably being the other extreme). I'm not certain about the burn-in time.