Class A ADCOM Car amplifier at home

[Kannan]

Had been eyeing Class A amps for sometime, but could not find anything in my budget.

Then managed to procure a well received ADCOM 2-channel vintage car audio amplifier.

Model GFA-4302: Looks like a dual mono design as it has separate gain pot for each channel.

Class A operation to the MosFets with all gain stages up to the outputs in pure, single ended (asymmetric) class A
30 watts per channel into 4 ohms (100 watts mono)
Frequency response: 0Hz to 50kHz
Signal to noise ratio: 100dB
Channel separation: 90dB
Damping factor: 350
Input sensitivity: 400mV to 2V

Associated Equipment:
A 220 to 14 volt SMPS based inverter
Laptop with Plex server
DAC-cum-preamp: Chromecast Audio
Chromecast Audio analogue output connected directly to the ADCOM amp
Heavily modded Infinity Reference 425 2-way bookshelf speakers
Basic MX 3.5 mm to RCA cable between the Chromecast and the amp
16 awg OFC multistrand speaker cable
Handmade stand using tree trunks

Pitfalls:
Boxy untreated room, 25 dollar DAC, wireless streaming, average quality interconnect

Listening:
As the amp was unused for almost 5/6 years, it took almost 4 hours of run to open up and then it was just mellifluous.
One word 'goosebumps', incredible control over the drivers, absolutely lush midrange, excellent integration to the lows (though does not go very deep but clean and taut), reasonably detailed and smooth highs, absolutely non fatiguing.
Spot on imaging and a wide stage.
Did a long listening session of almost 20 hours with 2 short breaks.
Listened to a wide range of music.

NAD3020 has gone into cold storage

Links:
https://goo.gl/photos/9dpFJ4R35sNk8ntG9

https://goo.gl/photos/YCAsUTv1meCVpJRA6

 

[Kannan]

Upgraded the chain with Teac UD301 dual mono DAC.
Toslink output from Chromecast Audio to TEAC optical input with an Audioquest cable.
Have the Schiit SYS between the DAC and power amp.

Impressions:
The TEAC is clearly far superior with more body to the music, lows go that much more deep, highs are much smoother with better layering overall, instruments are less cluttered, stage is far wider with a much deeper focus, feels as if the front wall have moved a few feet further away. Midrange is exceptional as was with the Chromecast aswell, but this is a more organic and sounds less digital.

The dual mono design with my dual mono amp seems to be working well.
Next is the upgrade to Blue Jeans interconnects which should be with me by end Sept.

But Chromecast by itself is phenomenal, just that TEAC does things at a more superior level.

For someone on a budget, or wants to start out on his audio journey Chromecast is absolutely unbeatable and comes highly recommended from me. it can compare with any sub 150 dollar DACs in the market.

Next update on this audio journey will be the tube buffer after all the 4 varieties of tubes arrive.

 

[Kannan]

Update: The Teac has improved by leaps and bounds as it has done more than 500 hours.
(yeah I listen on an average for 2/3 hours on most days into the night).

The Yaqin tube buffer was excellent with the Parasound DAC but I like the Teac without the buffer and it is now up for sale.

The preamp of Teac uses two muses8920 opamps (one for each channel) which has been very nicely implemented. I would have also enjoyed independent volume control for each channel.
The pre of the Teac is easily able to drive my Adcom amp, bringing end to my look out for a separate preamp for now.

Overall the setup is nicely balanced and non fatiguing and Teac is surely for keeps.

I am not a headphone guy so cannot comment on its headphone implementation.

But one thing i noticed is that it is not able to drive some headphones, eg it easily drives my Sennheiser HD598se but was not able to drive the more demanding Massdrop AKG K7xx that my friend owns.