A valve amplifier against a solid-state one. They are not really rivals: they differ in character, in what they will drive and in what owning them involves, so start there rather than with the watts.
| Area | Better | Why |
|---|
| Power | A | PS Audio BHK Mono 300 has more power - 300W against 100W into 8 ohms. That is about 4.8dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Room size | depends | We rate PS Audio BHK Mono 300 the better fit for a very large room, and Cambridge Audio Edge A for desk or near-field listening, a small room and a mid-size room. Match the amplifier to the room you actually have, not the one you want. |
| Grip on hard loads | evenly matched | Both behave much the same into 4 ohms - output nearly doubles (600W and 200W). |
| Noise floor | B | Cambridge Audio Edge A is the quieter design on paper - 103dB against 85dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | B | Cambridge Audio Edge A has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Analogue inputs | B | Cambridge Audio Edge A takes more analogue sources - 3 against 1. |
| Use with a TV | depends | Only Cambridge Audio Edge A has HDMI ARC, so the television can drive it directly and one remote controls the volume. If the system is for music only, this changes nothing. |
| Headphones | depends | Only Cambridge Audio Edge A has a headphone output. Worth something if you listen late, nothing if you never do. |
| Amplifier type | depends | PS Audio BHK Mono 300 is Hybrid and Cambridge Audio Edge A is Solid State. Valve designs are usually warmer and softer at the limits and need their tubes replaced eventually; solid state is the lower-maintenance choice. This is a taste and ownership decision, not a quality one. |
| Shelf space | depends | PS Audio BHK Mono 300 takes up about 17% less shelf area (1544cm² against 1867cm²), and it is 49mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Cambridge Audio Edge A costs less - $6,499 against $8,499 at list. |
| Watts per dollar | A | PS Audio BHK Mono 300 is the cheaper watt - about $28 per watt against $65. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A PS Audio BHK Mono 300 B Cambridge Audio Edge A
depends neither is better in the abstract - it turns on your room, your system or how you will use them. Only specs published for both amplifiers are judged; anything missing on either side is left out rather than guessed.
Which should you choose?
Cambridge Audio Edge A has the edge on paper, though not by much. The rows marked "depends" are more likely to decide this than the score is. Start with the room. In a large or open-plan room, or with speakers that are hard to drive - low sensitivity, or an impedance that dips - PS Audio BHK Mono 300 has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 100 watts is already more than most people ever use, and the extra 200 watts would be headroom you pay for and never hear - we rate PS Audio BHK Mono 300 poorly for near-field use for exactly that reason. If this sits under a television, Cambridge Audio Edge A is the one to buy - HDMI ARC means the TV remote controls the volume and there is no second box in the way.
What a spec sheet cannot show: how either sounds with your speakers, how the controls feel day to day, and what the app is like to live with - which is where most all-in-one amplifiers are actually won or lost. Power figures are the manufacturers' own and are not measured to a common standard, so treat small differences as noise. If you can hear both, that will tell you more than any row above.