The Ref 20's are Analog Switching Amplifiers
using their own unique circuit design, substantially different than class D designs that use standard and modified ICE and Hypex chips. The 20's leave Class D weaknesses behind, with sweet liquid shimmering highs, natural mids with timbral density, and killer bass. There are excellent reviews online and in TAS (Editor's Choice Award) for the Reference 18 and 20 so I will stick with my own impressions.
The 20's have excellent sound-stage depth and allow the instruments on the edges and background to sound more realistic with more bloom and air. They have incredible micro and macro detail and at the same time are refined and relaxed. For example, listening to Caverna Magica there is a couple very softly speaking at the back of a cave nearly obscured by more prominent sounds - with most amps you can barely tell they are there, with better amps you pick up that they might be speaking French; with the 20's I can easily follow whole sentences. Singers who slur or mumble words, are clearer and yet natural. Close-miked harmonica and female singers which can be grating at high volume, are just clean and present with the 20's. Attack/decay, speed, PRAT, and punch are excellent. The 20's bass is the best I have heard, with excellent weight, slam, bloom, and differentiation. RMS: 200W in 8 ohm, 420 into 4 ohm, Peak 400W into 8ohm, 800W into 4, stable into 2 ohm.
The $1,500 Bob Smith, factory approved upgrades preserve the original genius circuitry of the 20s yet remove nearly imperceptible RFI, EMI and vibrational distortion, and increase quiet by using increase shielding, high quality copper ribbon wiring and a stabilized power supply. I personally think that the modded 20's can complete at the $50,000 amp level and be preferred by many music lovers. I preferred the Nuforce/Nuprime Reference 20 monoblocks in my $150,000 system, to auditioned Merrill, Hypheus, Chanel Island, Hegel, Pass Labs, and Constellation.
I am original owner purchased 2015, modded 2017. Smoke free home. No Scratches, excellent appearance and perfect mechanically, all original packing. Original purchase price $7,600 + $1,500 mods = $9,100. I am selling $3,800 for the monoblock pair. 100% feedback on A'gon under gammajo.
