@carlsbad2 - Jerry, you’re on the right track, but I’m not sure the Anthem will like, or work correctly, using two inputs from different sources.
The correct way of doing things, and I have extensive and recent experience of doing this, as I wanted to find the same solution as the OP; is to get a pre-amp with a ’Pass Through’ input arrangement. Sometimes named as a ’Processor’ input. That will be your challenge; to find one, and within your budget.
The 'Pass Through' is just as it says, it will pass through the signals coming out of your Rx's (Rx = Receiver btw) main L/R pre outs to the input of the pass through section of the pre, at FULL Volume, so the Rx will be controlling the final volume, so you must use the Rx's speakers output level section to get the volume correct on all 5, or more, channels. If you don't use a pre with a pass through facility, and use any 'normal' input for your Rx's L/R pre outs, every time you alter the volume on the Rx, you will then have to adjust the volume on the pre to match = a PitA! (I know, I've done it, as I used an ARC LS3b for a time)
Before I go on - OP, you will get a MASSIVE improvement in SQ by ditching the poor quality pre-amp section in your Rx . I’ve used the pre-amp sections of a TotR Denon and TotR Onky Rx, each costing over £3k and earlier this year I decided to try what the OP is asking, and, what a revalation, going into my Threshold Stasis 3 S300II/Magneplanar 1.7i’s (previously JBL L-100 Century, so no comments about the 220wpc Rx into a difficult 4Ω load of the 1.7i). I didn’t have a great amount of cash, so the cheapest ’half decent’ Pre with the aforementioned pass through was a NAIM 122x. This killed the Pre section of my Onkyo TX-NR5010 and proved I was on the right track, but I thought; this could be better, so I swopped the 122x for the next model up the range, the NAIM 202 - another improvement, which I stayed with for c2 Months.
Then a friend brought round an Audio Research LS3b, and although no pass through, it was an OMG moment; the NAIM went up for sale and an ARC pre was hunted for, not as easy as you may think. I contacted almost every ’high end’ Hi-Fi dealer in the UK (including the UK ARC importers) asking if they get offered an ARC LS17/26/27 or if the price was right a Ref 3, to contact me and I would buy it. After 3 Months, nothing! Nothing even on the bay! Finally, I found a Ref 3 at the right price and it was bought, and I’m now in 7th heaven.
The Processor input is used when watching movies as it takes the input from the Tx L/R Pre Outs, but then I use the CD input, or whatever, to listen to Stereo - perfect.
Apologies for the long reply, but I thought it may give the OP a road to follow which WILL give him, and maybe others, a pronounced SQ improvement over the poor quality of Rx pre-amp sections, and all the associated garbage that’s contained within those signals from the Rx’s innards.