the cart or the horse?

With those speakers as many have said a good tube amp.  Doesn't have to be super powerful.  I bought a used Decware Mini Torii ( $1100.00) to use with my 92b Ref 3A de Capos speakers.  it's plenty loud those Omegas should sing with 4 watts.

look around take you time and invest in some good clean used gear.

Dump the loudspeakers, the amp and the preamp.  Stretch you budget a little and get KEF LS50 Wireless IIs.  I agree with all those who stated that your current system is mismatched.  I even agree with those who say your Omegas are a real good loudspeaker.  I just think that getting a good sonic match for the Omegas will give you a somewhat complicated system.  The KEFs will produce high quality sound while keeping it simple and allow for future upgrades.  New they are $2800.

BTW, how did you come about picking the Omegas?

I'm in a different camp than most of the folks that posted here (and I'll likely get blasted for it). I would encourage wavendon to explore some reconditioned vintage tube or solid state integrated amps or receivers. If you can find something with variable loudness controls, that can make a very big difference listening at low volumes. I believe the lower powered solid state gear from the late 60's and early 70's has a very nice tone and sound quality, and the tube gear from the 60's sounds absolutely wonderful. Both of these should be a decent match for your speakers. My current favorites (in no particular order) from extended listening periods with moderately efficient speakers are:

Sansui 777a

Marantz 2215

Marantz 1060

Luxman R1070

Harmon Kardon 330c (the 330b might be even better)

McIntosh MA6200

Fisher X-202-B

Scott 222B

Most of these can be purchased in recapped/serviced condition ready to play for many more years for less than $1000, and some way less than $1000. Good luck on your journey. Feel free to PM me if you want more details on any of the pieces I mentioned. I've spent many many hours with all these and know them well.   

Keep your speakers. 
 

sell your other gear (keep the Node) and start here with this small tube amp that sounds fantastic for the $$$$.

I have no affiliation with TMR.

This is what AGon should be all about. Great thread. Enjoyed reading this…