The single biggest upgrade to the musicality and quality of my system has been the result of the addition of the Audio Note Kit 1 300B Single-Ended amplifier. I am absolutely thrilled!
A spectacular-sounding 300B, single-ended integrated amp. I loved the experience of building this baby from a kit and the sound is sublime. A huge upgrade over the Manley Mahi/Manley Shrimp combo I had previously.
SOTA Sapphire
Recently upgraded this 'table with new titanium bearing, new, series V springs, new belt and dust cover.
Linn Basik-LVX
It's what I've got. :-)
Ortofon 2M blue
Not much to compare it to but well reviewed at the price.
Bottlehead Seduction
2-tube phono preamp
Music Hall CD 25.2
Beautiful build quality, great sound at the price.
Supra Classic 6.0
Bobby Palkovic of Merlin told me to look for a 9 gauge, stranded copper wire, and this is what I found. It's unique in that each copper strand is plated with tin, to insulate the strand and reduce "skin effect." The result is a cable that is, in Bobby's words, "stupid good," especially at the price. A 3 meter pair with spade connectors cost me $103 with shipping, direct from the distributor, Sjofn HiFi.
Musical Fidelity M1 DAC
Perhaps the single best upgrade I've made to my system, other than my speakers and new Audio Note Kits Kit 1 amp. A steal at the sale price from Needle Doctor, it has lifted the Musical Hall CD player to new heights.
Reference 3A MM De Capo iA
Latest version of this classic monitor. The white Surreal Acoustic Lens in the middle of the main driver is said to improve dispersion and clarity. They sound wonderful. Update, March, 2013: I have upgraded the tweeters to the latest, beryllium tweeters from Reference 3A.