Which Pre-amps Will Allow Two Subs

Which preamps will allow this naturally and easily? Thanks in advance for your help all.

I think the ARC LS12 has 3 outputs, 2 balanced and one single ended, all driven. You would most likely need an XLR to RCA converter for the sub but if your amps are being driven single ended this could be the ticket. Look into it though.
Try the Outlaw audio ICBM, stereo subs are better IMHO.

Are you interested in feeding the left channel to one sub and the right channel to the other? Or summed left and right to both subs?

In the first case, any preamp with two sets of outputs would work. I know of several with dual RCA outputs: Kora Eclipse, Anthem Pre 2L SE, Aloia 11.01. And a couple with one XLR and one RCA output: Threshold Stasis-R 3.0 or any BAT VK 30 or 31. Many others also will have dual outputs.

If you want summed left and right to both subs, you could accomplish that with "Y" cables and preamps with dual outputs (one output for the main amp/speakers and the other for the "Y" cables to the subs) or find a preamp with 3 sets of outputs, such as suggested by "Shion ca".

What kind of inputs does your amp have? What kind of inputs do your subs have?

Disclaimer: I have some of the preamps listed above for sale now or may in the future.

For music the Linn Kairn will give you 3 set of stereo outputs for multi amps. For a home theater the Rotel RSP-1098 has dual sub outputs, keep in mind that they are feed the same signal (mono .1).
The Bryston BP25 has 2 sets of RCA stereo outputs and one set of XLR stereo outputs. This pre is robust enough to drive long interconnects; if your subs will be far from your pre, it should be on your list.
McIntosh preamps have 3 outputs as well.
First Sound Presence Deluxe Mk II has two sets of outputs as well...
The Pass Labs X0.2 have two pairs of variable XLR and two pairs of variable RCA. All usable at the same time with its single volume control or remote. The Pass X1 and X2.5 have one pair of each type that are variable.

I use my X0.2 with multiple amps and will use it with active crossovers eventually. Works simply and flawlessly.

It should be easy to use the RCA connectors for the Subs on any of the units. Remember that on preamps, the RCA outputs will have a lower output than the XLR, but almost all amplified subs have output controls on them to compensate for this little bit of difference.

Also if you ever run a Theater preamp through it, all three of these have a unity gain pass through for that purpose.

Hope that helps.

Best Regards,
To answer a question, I guess I'm looking at the subs as a left right channel thingy (technical enough). To everyone else, thank you so much. I have one of those 300b amps with a volume control. My speakers are not full range as they are single driver crossoverless design. So the next tier of additions will be a pre-amp, followed by a subwoofer. But since I was going to get one sub, shouldn't I make sure I get the ability to run two given that so many claim that 2 is noticably better than one?