A processor is an AV receiver with the amplifiers removed: it does the switching, decoding and room correction, and hands amplification to dedicated power amps. Separates buy headroom, flexibility and an upgrade path, at meaningfully higher cost and complexity. Most living rooms do not need them.
Why split the box at all? Because amplifiers and processors age differently. HDMI standards, decoders and room-correction platforms move every few years; a good power amp is more or less finished technology and lasts decades. Separating them means you replace the processor when the format changes and keep the amps. It also means each part gets its own power supply and chassis, so the amplifier section is not sharing a heatsink with a video board, and the processor's analogue stages are not sitting next to a bank of transformers.
Who needs them: dedicated theatres running at reference levels, demanding speakers (low sensitivity or awkward impedance), systems beyond nine channels where a single receiver's amplification stops making sense, and staged upgraders who want to build over years rather than replace every cycle. In those rooms the headroom is audible and the flexibility is worth the extra boxes.
Who does not: most living-room systems. A good AVR delivers most of the result for a fraction of the cost, and the difference between it and separates in an ordinary room at ordinary volumes is smaller than the difference between two speaker choices. Adding a rack, more cables, more heat and more things to switch on does not improve dialogue intelligibility on a Tuesday night.
Is there a middle path? Yes: an AVR with pre-outs, plus an external power amp for the front three when and if you need it. That covers the demanding-speaker case and the loud-room case without going to a full processor.
If you are unsure whether you are a separates customer, you are probably not yet, and that is a compliment to modern receivers rather than a criticism of your ears. When the room, the speakers or the channel count starts asking for it, you will know, and the question changes from "should I" to "which".
Tell us the room, the speakers and the channel count you are planning and I will say which side of that line you are on.
Not sure what fits your room and budget? Share your room size and budget on WhatsApp. It is a two-minute answer with a floor plan.
