2A3 tube amp - Grant Fidelity MS-2a3
Oct 10, 2013 at 7:32 PM Thread Starter Post #1 of 3


New Head-Fier
Apr 19, 2012
So I am finally dipping my toe in the world of head-fi. After much research and some advice from local head-lebrity Skylab, I picked up a pair of Beyerdymnamic DT990 (250Ω) headphones. I am running them on the headphone output of my beautiful and rare Grant Fidelity MS-2a3 amplifier. The amp provides 14 watts of 2a3 goodness per channel on it's speaker outputs and has plenty of power to drive the Beyers.

I am still learning about impedance matching. My question is this, am I OK running these 250 Ohm headphones on this amp? I have not seen a ton of documentation on the headphone circuitry aside from the line "Tube headphone output on 2A3 circuit" on the Grant Fidelity Product page ( http://www.grantfidelity.com/site/Grant_Fidelity_MS2A3_integrated_tube_amplifier ) I know this amp is based on the Yaqin MS-2a3 integrated, however there are some differences according to the folks at GF when i traded emails with them. I do not know exactly what they are, though I am positive they are upgrades on the Yaqin version. :)

And an off shoot question: this amp is made to drive speakers as well as headphones. Do I NEED to have speakers hooked up to this tube amp? I know not to run a tube amp with no load. When i plug into the 1/4 socket, i hear the amps relays click and the blue HEADPHONE light comes on so I know the load is routed properly. Would it damage that amp if I unplugged my headphones from the amp while it was on with no speakers attached?

If I want to swap headphones during a listening session, is it recommended that I power the amp down before making the swap? (I have a pair of AKG K701s on the way.)

thanks for reading. :)


Gear porn:
Oct 15, 2013 at 2:52 AM Post #3 of 3


500+ Head-Fier
Aug 18, 2013
I am getting a custom 2A3 integrated amp with a headphone output built for me which is going to arrive in a few weeks.

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