Start with an Android phone with sufficient storage capability and a decent DAC/headphone amplifier. Built-in is great; otherwise, find something that works and doesn’t suck up too much power.

Add IEMs of choice, for less than $50, or cans that are reasonably efficient. It stops being so portable if you have 800g cans and a 500g battery-powered amp to drive them.

Install F-Droid, and use that to install Vanilla Music and RootlessJamesDSP.

Configure Vanilla Music to point to your music data.

Use ADB to enable RootlessJamesDSP (it needs 2-3 android system permissions).

Download convolution equalization for your IEMs or cans. https://autoeq.app is an acceptable and very convenient source. If Oratory1990 covers your equipment ( https://old.reddit.com/r/oratory1990/wiki/index/list_of_presets ) then choose that, first.

Apply in RootlessJamesDSP.

Enjoy.

-30-

Previously:

In the office, my desktop feeds an Apple USB-C DAC ($9, no sale needed) to an optoisolator to a NAD 712 stereo receiver. I bought the NAD in 1998, new, no discount. It has a 1/4” headphone jack which automatically disconnects the speaker connections – a pair of Paradigm Monitor 3 Mark 3s. The usual headphones are Superlux 688b, Truthear Zeros, TRN V90s, or occasionally Sennheiser 280HDpro. The desktop runs equalization software (PulseEffects on top of PipeWire) that corrects each output, though it does have to be selected whenever I change outputs. The Paradigms were purchased used from a guy driving a white van, for $200 the pair – an excellent value.

Now:

My desktop is connected to a Topping MX3s ($199) via USB. The MX3s is a tiny box – about one quarter of a standard box of tissues – with a USB DAC, a headphone amplifier, and a 50W (4 Ohm) stereo amplifier. Yes, for real speakers. This is basically the same power output as the NAD 712, which is merely six times the weight and half the power efficiency. The headphone jack is 1/8” and does not automatically disconnect speakers, but the front button allows selection of headphones, speakers, or both. All other bits remain the same.

It’s really quite nice.