the tube in the tonebone does actually glow and no LED trickery is involved. however i believe the tube is more for toneshaping, the initial clipping section is diode based. someone correct me if im wrong. i did hear a noticeable difference when swapping out the 12AX7 tube for a 5751.
hung bro's is selling the tonebone for $375 i believe..
i have one for sale at $300. mint condition,i bought it in london in september and only used it a few times before switching to a J&H. original packaging,manuals and i'll throw in the 5751 tube for lower gain. PM me if interested.