That's the term that guitar legend Steve Morse used (coined?) to describe the music he writes and plays with the Dixie Dregs (a group which consists of guitar, bass, drums, keys, and violin). As this article notes:
Taking the fusion idea to its logical extreme, the band melded strains of bluegrass, Southern rock, and classical into a boiling cauldron of distinctly American, and sometimes blindingly fast, instrumentals they've referred to as "electric chamber music."
I should note that, among their different styles, the instrumental rock element is dominant.
This style -- what Morse refers to as electric chamber music -- is one of my favorites. Electric chamber music could also describe the music of some of the so called "progressive rock" (or "art rock") artists. Kansas, like the Dixie Dregs and Mahavishnu Orchestra (and a few other bands) also featured the guitar/bass/drums/violin/keys line-up. And "electric chamber music" certainly describes much of their music. Indeed, Steve Morse briefly joined Kansas in the 80s and put out two decent albums. (They could have been a lot better; some prog rock groups -- Yes, Genesis, ELP, Rush -- have had a few big AOR "hits" which have made record companies far more $$ than their ten minute long suite form epics. And so the pressure was on for Kansas to produce such a "hit" in the 80s. These two AOR genre albums flopped. They actually got rid of the violin; but with Morse, of course, there are smoking guitar solos. Those albums are worth it just for the guitar solos.)
Anyway I just got news that original violinist with Kansas, Robbie Steinhardt, is out and David Ragsdale, who replaced Steinhardt in the 1990s, is back in. While Steinhardt's presence in the band adds to the nostalgia, Ragsdale is a significantly better violinist (indeed, when original members are replaced in established bands, their replacements are almost always better technical players, though not necessarily better "artists." For instance, Sammy Hagar is a better singer than David Lee Roth; Steve Vai is a better guitarist than Eddie Van Halen; Ronnie James Dio is a better singer than Ozzy Osbourne; Randy Rhoads was a better guitarist than Tony Iommi, etc. etc.).
Anyway here is a 9:30 minute clip of Kansas in 1995, featuring David Ragsdale, which is in my opinion, electric chamber music at its finest. Note Steve Walsh's voice is a lot rougher than it was in the 70s (excessive screaming has caused a lot of rockers to lose the tone in their voice as they age); but he still puts his heart & soul into every note and phrases brilliantly.
I look forward to seeing them with Ragsdale the next time they come around.