What should I upgrade?

I don't own nor have I heard any of the gear in this thread. But I DO own some Martin Logans and love them.

My semi-educated suggestion would be to treat your room with bass traps in all four corners (I use Auralex) to reduce the boom and clean up your transients which are actually mid range frequencies. Your room is an echo chamber. You have to soak up the bad stuff before you venture into refined bass response. You'll be amazed at the difference and have a good starting point for "real" bass.

Then audition a Fathom (or a SVS PB13 for less money) to give you the best of both worlds. Clean and powerful.

I have an SVS PC13 that was $1500 new and blends well with my panels.

FWIW from a mid-fi enthusiast.

Brewed

Sorry I forgot to mention I have a pitched roof. on one sid it starts at 8ft and goes to 12ft. there are also 7 exposed wood beams that run along the ceiling. Where would I place bass traps and/or acoustic panels?

I believe that a pitched roof with beams on the ceiling will actually help break up any unwanted bass modes.

Before we worry about bass traps, perhaps we should get some bass first ; )

Rich

You need one Jl Audio F 113 or two of the smaller F 112 which are magnificent subwoofers.

Your room is huge, and the Maggies 1.6 are really too small for this size room 3.6 would be better,

More power couldn't hurt either it depends on how loud you play and how far away from the speaker you are.

The JL audio subs are really fast and blend well with these types of speakers, one of my customers had this subwoofer with a pair of $45,000.00 Scaena loudspeakers and the woofer could blend with this speaker which is really fast as well.

what cables are you using? more power would be great, two subs would be great, sure. but i would make sure that you're getting all the bass you can out of your system first to see where you stand.

i've never owned maggies and i don't know how sensitive they are to cables, but all the speakers that i've owned have been very responsive to different cables, particularly where bass is concerned.

i would think that the s300s would be able to get close to getting the lowest bass out of those speakers at low volumes, but (at least in my experience) that assumes that you've got good speaker cables and power cables on your components.

in my system, power cables on the components are as important as speaker cables for bass. recently i just got some nice (cryo'ed, for what that's worth) adapters to allow the use of 15amp power cables on c7 connections (those little 2-holed connections found on playstations and mass market electronics) and the difference on both my ps1 cd player and my hd cable box was great - the primary benefit being more bass. the two components had already been using a ps audio punch cable, which was a night and day difference over the tiny, stock cables, but using an even bigger/better cable was another jump.

so i would make sure all that is in place before spending tons on new amps.