I haven't heard either amp, but in comparing them, some differences stand out (and reflected in the Hlly TAMP-90 being ~ 2X the price of the Dayton DTA-100a).
Hlly TAMP-90
- 60W/ch @ 8 ohm, .1% THD
- 4 ohm minimum load
- Internal linear power supply with toroidal transformer
- 5-way binding posts
Dayton DTA-100a
- 30W/ch @ 8 ohm, .1% THD (50W/ch rating is at 5% THD)
- 6 ohm minimum load
- External switch-mode power supply brick
- Banana plugs only (included)
Steve