No single best amplifier here. What decides it is what you have to drive, what you need to plug in, and how much of the system you want in one box.
| Area | Better | Why |
|---|
| Power | A | Emotiva BasX TA2+ has more power - 135W against 80W into 8 ohms. That is about 2.3dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Room size | depends | We rate Emotiva BasX TA2+ the better fit for a large room and a very large room, and Cambridge Audio CXA81 for a small room. Match the amplifier to the room you actually have, not the one you want. |
| Grip on hard loads | A | Emotiva BasX TA2+ holds up better into a 4-ohm load: its output nearly doubles to 250W, where the other increases strongly. That matters with demanding speakers far more than the 8-ohm figure does. |
| Noise floor | A | Emotiva BasX TA2+ is the quieter design on paper - 120dB against 105dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | B | Both decode on board, but only Cambridge Audio CXA81 handles DSD. |
| Analogue inputs | B | Cambridge Audio CXA81 takes more analogue sources - 5 against 4. |
| Phono stage | depends | Emotiva BasX TA2+ has a built-in phono stage (MM and MC, 47k ohm MM, selectable 47 or 100 ohm MC) and Cambridge Audio CXA81 does not. Decisive if you own a turntable, completely irrelevant if you do not - and an outboard phono stage is easy to add later either way. |
| Room to grow | evenly matched | The same expansion options on both. |
| Price | A | Emotiva BasX TA2+ costs less - $1,299 against $1,499 at list. |
| Watts per dollar | A | Emotiva BasX TA2+ is the cheaper watt - about $10 per watt against $19. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Emotiva BasX TA2+ B Cambridge Audio CXA81
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?
Emotiva BasX TA2+ is the easier recommendation: it leads on most of the measured areas and costs less. Take Cambridge Audio CXA81 if one of the "depends" rows above describes your system. If your speakers are a difficult load - 4 ohms nominal, big woofers, or a sensitivity in the low 80s - Emotiva BasX TA2+ is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating. 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 - Emotiva BasX TA2+ has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 80 watts is already more than most people ever use, and the extra 55 watts would be headroom you pay for and never hear - we rate Emotiva BasX TA2+ poorly for near-field use for exactly that reason.
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.