The Parasound A23/A21 can do this.
Pre/Pro for bi-amping (5.1 configuration)
I have been using my Pioneer Elite SC-65 (using it as a pre/pro) to bi-amp my Bryston Mini-Ts via an Anthem PVA-7. The Pioneer Elite SC-65 has in it's programming the capabilities to drive/send the low frequencies to the woofers on the front speakers using the "normal" and the upper frequencies to mids and tweeters by configuring the surround channels. I am using this as a 5.1 configuration!
I'm looking to update my Elite SC-65 as it's starting to act up. I would like to find a pre/pro that does something very similar that the SC-65 and not just use a Y-adapter as a cheap fix. (See attached screenshot of the SC-65 manual)
There is noticeable difference between standard connectivity from the SC-65 through the Anthem PVA-7 to the Mini-T's versus the bi-amping through the SC-65 and the Anthem PVA-7 to the Mini-T's It's truly noticeable the difference it makes. Just tonight I had to reset the SC-65 to factory default so I listened a while in stand configuration then re-did everything to bi-amping (changed software in the SC-65 and wiring to the speakers) really noticeable and much enjoyable in the bi-amp configuration.
So what would be a good pre/pro to replace the Pioneer Elite SC-65 with something that has true bi-amping within the unit?