It is mostly old/new "garage bands", plus punk, 60's bubblegum pop, new alternative/college bands and anything else the DJ's or SVZ desires. I think it's better explained with a link:Sirius Underground Garage Note that the short list of artists "The Ramones, The White Stripes, MC5...
The Bridge is now E Street Radio - 24/7 Springsteen. I would say Sirius Disorder is probably closest to The Loft, but a little more Alternative. The Coffee House also does older, jazz artists - Ray Charles, Louis Armstrong, but it is a great relaxing channel. For sheer musical knowledge and...