Why buy the active circuit in the Adcom when you're not going to use it? Instead, you can get a $60 ladder attenuator at s/one like these guys. Buy a box, input connectors, connect the above & you're in business! You'll have to check the impedance synergies of course -- but the vendor can surely help here.
Otherwise, and if finances permit, go for a TVC.
Otherwise, and if finances permit, go for a TVC.