Subwoofer advice please

[jzzmusician]

I'm hoping to find a little bit of clarity with your help.

I've got the itch to buy a pair of modestly priced subs, (SVS SB13 Ultra or REL S/3 SHO).

Here is my dilemma; I use a PrimaLuna Dialogue Premium HP driving a pair of rebuilt and completely upgraded Quad 2805 speakers.

The PrimaLuna has one subwoofer out. Okay, great I think.

My dilemma is when I research proper subwoofer integration almost all posts and articles state that an external crossover is needed to really dial in the sound.

Obviously I can't do that with the PrimaLuna.

It would be less expensive to sell the Quads and upgrade, (a topic I'd love to talk about) than to buy a new front end and hope that the subs worked out for me.

Any help or advice is greatly appreciated and if you're ever in SE Washington state I would repay your kind advice with world class bbq and cool, refreshing beverages.

Thank you in advance,

Bob