These are not the same size of amplifier: Sony STR-DH190 has roughly 3x the power of Onkyo A-9110. That is about 4.8dB, so it is a question of room size and how hard your speakers are to drive, not of one being the better amplifier.
| Area | Better | Why |
|---|
| Power | B | Sony STR-DH190 has more power - 90W against 30W into 8 ohms. That is about 4.8dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Price | B | Sony STR-DH190 costs less - $248 against $349 at list. |
| Watts per dollar | B | Sony STR-DH190 is the cheaper watt - about $3 per watt against $12. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Onkyo A-9110 B Sony STR-DH190
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?
Sony STR-DH190 is the easier recommendation: it leads on most of the measured areas and costs less. Take Onkyo A-9110 if one of the "depends" rows above describes your system. 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 - Sony STR-DH190 has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 30 watts is already more than most people ever use, and the extra 60 watts would be headroom you pay for and never hear. Think about the whole system: the roughly $101 saved by taking the cheaper one would buy better speakers or a subwoofer, which does more for the sound than the difference between two competent amplifiers.
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.