Biggest "bang for the buck" audio gear you have owned(in your history)?


This is very subjective, and your opinion on your own systems/items is all that really counts.

From the beginning to now, these would fit that category for me: (in no order)

Original Large Advents
Dahlquist DQ-10
Conrad Johnson ART pre.
Original Monster interconnects and speaker wires.
Nakamichi SR-3a
AR Turntable
ADC XLM II
Audio Research LS-12
Magnepan 1.6
Magnepan 20
Wireworld Gold Eclipse III
Audio Technica Electret Condenser headphones 
Magnum Dynalab Etude and 108 tuners
Magnum Dynalab Receiver (original)
And in those "early days" special pressings and imported Jazz albums. 

There may be others I am forgetting, but these were very good items along my journey. 





jusam
I downsized my $100k+ all Shindo rig to a pair of Kef LS50 Wireless II with matching KC-62 Sub. I'm not about to say it's better, (it's not) But running Roon directly into them it does blow the doors off most other systems I've heard at similar to double the price. None of which is important, what is important is that I now listen to it daily vs. having to find time to fire up and sit down to listen to the "big rig". Now I can sit and listen, have it in the background, crank it so I can hear it out on the deck, impress the neighbors etc...
Equitech 2RQMade my whole system sound like it was twice as expensive.That, or iFi Zen Blue bluetooth DAC. $129 streaming front end.$129 source connected to $18,000 worth of other components.Sounded pretty dang fine! Lumin U1 mini was big upgrade but cost 16 times as much. Doesn't sound 16 times better. Haha.
Rockwool. About $900. 
Made at least a 30% improvement to sound that I thought was already very good. 
I think the Thorens TD-160 I bought around '75...can't recall the price.  And most recently DQ 10's-$375 and a vintage Proton D540 with the Dynamic Power on Demand feature-$159.  Biggest sounding little amp I've ever heard.
Yamaha NS 1000's
Dayton Wright XG 10 Mk III's
Dayton Wright LCM1's
Threshold 4000
Citation FM Tuner