What's the weakest link in my stereo set up? I live in a townhome, so limited on space.

pair of restored AR3a’s near you

think of them as the smallest big speaker, easy to have refinished if you love them.

put them on stands, tilted back, toed-in: rear level controls for tweeter and mid range like my AR2ax’s which have 10" woofers, the AR-3’s have 12" woofers

"The Acoustic Research AR-3a Loudspeaker:

The AR-3a is a 3-way, full-range, 4-ohm acoustic-suspension loudspeaker—technically a bookshelf speaker for very sturdy bookshelves—which includes the well-known AR 12-inch acoustic-suspension woofer and dome midrange and tweeter drivers, based on the original AR-3.

The AR-3a was designed by Chuck McShane and Roy Allison of Acoustic Research, Inc., and the speaker was introduced at the New York High Fidelity Music Show in October, 1967. The basic design goals of the AR-3a were originally established in 1965-1966 by AR cofounder Edgar Villchur, with the objective of improving the already excellent off-axis dispersion of the renowned AR-3. The result was a speaker containing one of the widest and most uniform midrange and treble dispersion of any forward-facing loudspeaker ever designed for home sound reproduction.

The acoustically sealed, heavily braced (nine internal braces screwed and glued to the inside of the cabinet) and critically damped (the "Q" of the AR-3a is 0.9 - 1.0) AR-3a enclosure volume is 1.7 cu. ft., which is optimal for the 41-43 Hz resonance frequency, and the woofer’s suspension restoring force ratio is approximately 85% acoustic and 15% mechanical, far greater than nearly all current consumer loudspeakers using the a/s design. For this reason—and the basic design of the motor system in the AR woofer—the AR-3a has much lower harmonic distortion than any conventional, current-design loudspeaker of a comparable size. Julian Hirsch measured the woofer’s harmonic distortion at a power level ten-times higher than usual test input voltages, and the distortion in the AR-3a’s woofer was under 9% at 20 Hz, setting a new standard of low distortion, especially at this high-power testing.

The woofer used in this pair of AR-3a speakers has a large 9.6 lb Alnico-5 magnet assembly, cast-aluminum frame and a long-throw, 2-inch heavy copper voice coil with a linear excursion of 5/8-inch and a maximum physical excursion of 1.2 inches. The midrange driver has a 1½-inch treated-cloth dome (hemispherical) diaphragm with 1½-inch copper voice coil on an aluminum former assembly. The midrange driver is critically damped with fiberglass pads under and above the dome assembly itself. The magnet assembly is a large ferrite unit. The AR-3a tweeter uses a ¾-inch treated-paper dome diaphragm—similar to the original AR-3 phenolic-dome tweeter—suspended by urethane-polymer foam pieces in the outside portion of the voice coil with a layer of clear butyl-rubber sealing the outside of the magnetic gap. The magnet assembly is ferrite. The drivers have LCR crossover frequencies of 575 Hz and 5,000 Hz.

The speaker’s impedance ranges from 2.7 – 4.9 ohms, and the speaker is approximately 0.5% efficient, meaning that an amplifier capable of at least 30-50 watts-per-channel into 4 ohms is the minimum suitable power. The AR-3a physical dimensions are 14” x 25” x 11-3/8.” The AR-3a’s net weight, each, unboxed, is 54 lbs., and in the double shipping carton 64 lbs gross."

Ignore any of these people recommending something as ridiculous as upgraded cables and power cords.

Back here in reality, where science triumphs over snake oil marketing, I think you should start by looking at your room acoustics before buying any new gear.

Ignore the dullards who tell you cables don’t matter because of science. They know nothing about science and are too dumb to try something.
I note below where you can borrow cables to try out. 
 

Your equipment would benefit from good cables. You have entry level high end gear. You don’t mention what you are using for cables.

start with speaker cables. I will recommend kimber kable 4tc for your setup.

contact thecableco.com.
they will let you borrow a bunch of cables for a small fee (that’s put towards purchase). They may recommend other cables in your price range. Borrow and try them. Very worth it.

@sudnh I use Blue Jean cables for both speakers and interconnects. I've read many times they are not low end, but I'm also not spending hundreds of bucks on cables. 

Is there a brand you would recommend me try that is also "entry level high end" that isn't a laughable price?

I say this because 90% of thr cable threads I've read say most of the times it's snake oil. 

I'm interested in the times it's not. 

OP,

I recommend DHLabs interconnects and cables as a reasonable cost quality interconnect. I have these around a quality connectors when I get a new piece of equipment and want to spend the first six months with the new component, getting it broken in and getting to know the sound. 

Blue jeans are budget interconnects ... low end, often marginally better or not at all than consumer. I tried them to see just to see how they sounded. I have nearly fifty years of experience in high end audio. You can see my systems under my user ID. Everyone's system is different so the impact on the sound quality is highly variable. The difference in high end wires increases as the sensitivity of your system goes up. Typically the rule of thumb is think of spending 10% or so the value of your system. More or less can be appropriate. 

If you are reading cable threads that 90% of the time say it snake oil. You are reading the wrong threads. This is categorically wrong.