Question Pioneer A300R - Basic Headphones Sound Terrible


Novice Member
Hi Folks,

I use a Pioneer A300R amplifier (the Tom Evans "Precision" variant) that I recieved as a hand-me-down from my dad a few years ago. He purchased this amp back in 1989 (before I was born!) but it is still working very well. Since inheriting this amplifier, it's always worked well and to be honest it's in impressive condition for its age and how much use it gets.

I have never tried to use the 'phones' output on this amplifier until yesterday, when I received a cable that adapts the larger 6.35mm jack connection into a standard 3.5mm socket for my headphones. I was suprised when the output from the amp sounded absolutley awful through the headphones as I was expecting it to "just work".

My first thought was to blame the cable, but I did some research, and I think the issue is with impedence. Unfortunately, I couldn't find any specific information for the A300R that will help me narrow this down as the problem. I know that the Sennheiser Momentums are pretty basic and have a low impedance of around 18Ohms. The sound through them sounded fine through either the left OR right channel, but not both at the same time, which sounded garbeled - almost like it was running in slow motion.

I also have a Turtle Beach P11 gaming headset which features a USB powered in-line amplifier and I plugged this in. Not only does it work but it actually sounds pretty decent, even when I set my amp to output from my turntable. I'm thinking that this USB amp is somehow correcting the issues I experienced with my Sennheiser Momentums, but I lack the knowledge/experience to actually understand what's going on.

My reason for posting here is that I'm trying to understand this better as it's all quite new to me - and being vintage gear, information online is hard to find. If anyone who reads this may be able to explain to me what is happening here, I'd really appriciate it. If impedance is the problem, then I'll consider purchasing some high-impedance headphones. These are quite expensive, though, so I'd like to be sure that this is the issue first.



It could be that the jack socket needs some cleaning. Does the sound alter when you move the jack around? Your assertion that the low ohm ratings of the headphones could be proving problematic. Some headphone amps don't perform well with low impedance headphones and can give a certain amount of floor noise.

The good news is that it has a tape loop and so you could connect a standalone headphone amp to the Pioneer which will give a far superior performance. On many amps the headphone jack is put on as an after thought and are not great.

My amp doesn't have a headphone jack so a standalone headphone amp was essential and buying one proved a worthy investment as I do a lot of headphone listening.


Novice Member
I thought that dirt in the 'phones socket could've been the issue but this seems much less likely given the great (and to be honest, suprising) results I got from my USB powered Turtle Beach headset. Also, the sound doesn't change when I move the plug around in the socket.

Although the Turtle Beaches work, I'd much rather use "proper" headphones, like my Sennheisers - so I'll have a look into your suggestion to use a standalone headphone amp via the tape loop. Thanks!
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