No single best speaker here - they are built to different priorities, and the right one depends on your room, your amplifier and what you listen to.
| Area | Better | Why |
|---|
| Bass | B | KLH Concord digs deeper - 28Hz against 36Hz. A subwoofer would even that out. |
| Amplifier needs | B | KLH Concord is more sensitive (94dB vs 90dB), so it goes louder on the same amplifier. |
| Headroom | B | KLH Concord takes more power (225W vs 120W) - more in hand in a big room. |
| Size | depends | PSB Alpha T20 is easier to place; KLH Concord is bigger, which usually goes with fuller bass. Your room decides. |
| Expandability | A | PSB Alpha T20: bi-amping. |
| Price | A | PSB Alpha T20 is cheaper - $799 against $1,000, about 20% less. |
A PSB Alpha T20 B KLH Concord
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 speakers are judged; anything missing on either side is left out rather than guessed.
Which should you choose?
The usual trade-off: KLH Concord measures better, PSB Alpha T20 costs about about 25% more% less. Whether that gap is worth the money is the call only you can make - and in a normal room it is often smaller than the numbers suggest. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 36Hz anyway, which makes the cheaper PSB Alpha T20 much easier to justify. In a large or open-plan room, KLH Concord has the cabinet volume to fill it more easily; in a small room, near a wall or at desk distance, PSB Alpha T20 is the easier speaker to get right.
And remember what a spec sheet cannot show: how each looks in your room and whether the finish suits it, what dealer support and warranty are like where you live, and how they actually sound to you. If you can hear them first - ideally with your own music - that will tell you more than any number above.