Kinda but also kinda not. If you take out the jumpers you effectively stop using anything before the pre in. Yes you can add your own preamp and run multiple things in through it but you lose the NADs volume control and DAC and the MDC cards so no bulit in blueOS or DIRAC. You can get multiple source RCA switch boxes too but they’d be third party, I don’t think NAD makes one.
I think the transport probably is wisest option with this amp. Especially as transports are having a bit of a renaissance right now and as you don’t have any SACDs. From entry level with the three IAG brands (Audiolab/Quad/Leak) to surprisingly good and whilst expensive cheap when you consider the laser in it (Project RS2) to just the downright shockingly good but pricy (Jays and a few others) there are so many options right now.