The 85w of that Music Hall will give you about 1.5db more headroom over your 60w Allo. Even if you went for a 150w monster amp, it would be giving you only about 4db headroom. Adding a sub is better value, IMO. If you dial it in correctly, you will get lower distortion and greater frequency range response.
Of course, if you're set on an amp being the next step, I'll stop now. 
True about the 1.5 db but the Music Hall almost doubles it power at 4 ohms putting out 160wpc. That tells me that the power supply is robust and it probably is a high current design. Music will be more dynamic and punchy especially on peaks. The amp should not run out of steam. Bass should have more thump and the music should sound fuller. Those speakers are 90db, easy to drive and should play screaming loud at 85wpc. However, they are bookshelf speakers and a good sub would certainly fill in the bass and greatly improve the sound. Other advantages are that the MH has a DAC, Phono pre and it has a preamp out along with Bluetooth.
The power rating on the Volti amp is misleading. It says 60wpc but that is if you have a 23v PS. It comes with a 19v and is rated max 50 wpc at 4 and 8 ohm. Not so robust. Even at 50 wpc it should play very loud with 90db speakers at 8 ohm. So there is an obvious problem if the OP needs more volume. Here are the actual spec's-
FEATURES CLOSER LOOK TECH SPECS SUPPORT & DOWNLOADS
Technical Specifications
Chipset TPA3118D2
Output 2 x 50W (Max) into a 4 to 8-Ω BTL Load
Class D Operation 90% POWER EFFICIENCY
SNR 102dB
Supply Voltage UP TO 24V DC
Operating Temperature -40°C to 85°C Ambient
Board Size LWH = 82.83mm * 125.5mm * 40.2mm
DC Connector Size 3mm x 7.3mm
Mating Plug Size 3mm x 6.5mm
Board Weight 230g
TECHNICAL SPECIFICATIONS BR03
Number of drivers
2
Number of ways
2
Sensitivity
90 dB/W/m
Frequency range
46 Hz – 22 KHz (+/- 3 dB)
Power handling
100 W
Nominal impedance
8 Ω
Minimum impedance
4,2 Ω
High frequency roll-off
3600 Hz
Dimensions
206 x 380 x 314
Weight
6,26 kg
