Systen Upgrade advice

My current system componenets listed below. I am able to make some improvements. If this were your system what would you change out first for the biggest improvement? Thanks.

Audio Research SP8, Aragon 4004 MkII, Linn LP12/Ittok IV/BenzMicro Glider, DIY Hybrid OB Speakers, Velodyne HGS12, Emotiva ERC-3, Burson Conductor DAC, JK Ciunas USB Converter.
DH Labs, G Huffman, MIT 750, and PA Audio cables.
You make it hard because your speakers are a total unknown. The Aragon is probably the week link in your system but knowing nothing about your speakers I can't really recommend a different amplifier.
I understand Alan.
If it helps its a 3 way hybrid open baffle system. sb acoustics tweeter, peerless 6 inch mid and 10 inch woofer 88db sensitivity. I would say if i get another amp it should be similar in power (150-200 watts)

Thank you for taking the time to reply.
One other question
Also would you consider going tubes or do you want to stick with SS. For SS I would look at pass labs
For tuves The VAC stuff is really good.If you are on a budget I think some of the Emotiva amps would be an improvement over the Aragon
Solid state on a Power Amp. I am open to either on a Pre. This is #1 for reliability purposes and #2 I think that since the early 1990's there have been big improvements in solid state so a good SS component today is significantly improved (?). There are lots of tube stuff I salivate over (Manley, VAC, VTL etc)but out of my league. I would consider Pass. In fact I have been considering the X150. I was considering the Plinius but some have said they run even hotter than the Pass stuff and I have concerns with reliability/servicing of an item from overseas. At least I can get Pass equipment serviced.
Oops, didn't answer the important question. Budget is $2000 (a bit more if i have to)
BTW The budget is predicated on purchasing preowned equipment.
AC power isolation and conditioning will elevate your entire system. You might be quite satisfied. Worth a try.
Biggest improvement is always loudspeakers. It is at least until you run out of money.
Well, i am going to install a dedicated line from my fuse panel. I have monster power center, i'll have to check the model number. just bought hospital grade outlets
OK so I have an offer in on an amp lets see what happens. More to come :)
Update: I purchased a Modwright KWA 100 SE. I like the sound of it. It is an improvement and now I think I can focus on some cable improvements that are in the works (digital cable and power cables)n Thanks for the advice.