Fostex HP-A4 24-Bit Digital to Analog Converter/Headphone Amplifier

My setup: 2018 Mac mini (Mac OS 12.4, Monterey) > Fostex HP-A4 DAC/Amp (via included USB cable) > Headphones (Ultimate Ears UE 11 Pro IEM, Fostex TH-900, Denon D5200). Apple Music Lossles/Hi-Res Lossless music service. Setup works flawlessly.*Note: I have seen reviews here that state this does not work out of the box with Mac OS. That is NOT true today. This worked right out of the box for me, no drivers or additional software required - pure plug and play. Either Fostex or Apple has updated firmware/software to fix this sometime in the past.This is a great little simple to use box that works well at powering easy-ish headphones to drive (as all of mine listed above are). The input/output options are nice, and everything works as advertised. Volume knob is smooth and has enough resistance to provide feedback.Sound wise, I've found it to be neutral, meaning it doesn't add any noticeable (to me) color to tweaking to the sound, which is my preferences as I use it with several headphones. This is amp that does not provide a ton of power, since it is powered by USB. Most of the headphones that it will drive would likely get fairly loud without any amp at all. However, this DAC/Amp combo absolutely performs better than plugging directly into my Mac or iOS device. Cleaner sound with more even control at all volumes, better clarity at high volumes, less distortion.Very happy with this purchase!

Great for some video games that are super lag sensitive via HDMI (Rocksmith) just toslink in and you're good. It also plays DSD albums, sounds amazing. Overall great value and build quality for the price. Being able to turn headphones on/off independently is awesome you wouldn't think it would be a thing but it is when you have it.

There are a couple of reviews claiming this DAC doesn't work with macOS or with Windows 10. I can't speak to the Windows situation, although the manufacturer says the unit does work with Windows 10. But I have been using this DAC with a Mac for 4 years with no problem. I am still on macOS Mojave due to the need for an old piece of software (soon to be replaced). The Fostex HPA4 was the perfect compact solution to my use case. It is connected to my iMac via USB, connected to a pair of Adam speakers and a different brand of subwoofer via the RCA outputs (using a Y-splitter), and connected to headphones via the quarter-inch headphone jack. With with Output Select button, I can easily switch between the headphones and speakers — something I do often. The volume knob on the front is very handy too.

Beside the really great sound quality, I'd really recommend it for another reason.I was planning to use this with the SPIF connection as every single DAC amp I've tried would buzz when then plugged into my Monitor speakers.This was the first Dac amp that worked perfectly with USB, cancelling all buzz that my computer was generating with all other DACs. (The others being Schiit products as well as the monoprice dac)I highly recommend it.

The Mac will not recognize inputs or outputs in any way shape or form, nor is it in any way compatible with it. I am appalled by the deception of not including that this is not compatible with Mojave. If you own a Mac with the latest OS, do not buy this. It's a colossal waste of money.