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 | B | Mark Levinson No.5805 has more power - 125W against 100W into 8 ohms. That is about 1dB, which is a small step in loudness but real headroom on peaks. |
| Room size | depends | We rate T+A PA 2000 R the better fit for a small room, and Mark Levinson No.5805 for a large room and a very large room. Match the amplifier to the room you actually have, not the one you want. |
| Built-in DAC | B | Mark Levinson No.5805 has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Analogue inputs | A | T+A PA 2000 R takes more analogue sources - 5 against 3. |
| Phono stage | depends | Mark Levinson No.5805 has a built-in phono stage (MM,MC) and T+A PA 2000 R 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. |
| Shelf space | depends | T+A PA 2000 R takes up about 24% less shelf area (1863cm² against 2454cm²), and it is 154mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Mark Levinson No.5805 costs less - $10,500 against $11,490 at list. |
| Watts per dollar | B | Mark Levinson No.5805 is the cheaper watt - about $84 per watt against $115. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A T+A PA 2000 R B Mark Levinson No.5805
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?
Mark Levinson No.5805 has the edge on paper, though not by much. The rows marked "depends" are more likely to decide this than the score is. If you play records, Mark Levinson No.5805 saves you buying a phono stage; if you do not, ignore that row entirely. If you already own a DAC or a streamer, the built-in one is money you are paying twice for, and T+A PA 2000 R becomes the more rational buy.
What a spec sheet cannot show: how either sounds with your speakers, how the interface feels 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.