From QSC:

QSC designed the ISA 500Ti as a cost-effective solution specifically with sound contractors in mind. The ISA 500Ti can drive both eight and four ohm loads and a distributed system on the same channel at the same time, allowing you to reduce the number of amplifier channels needed to power the speakers from the same amp. This rugged power amp can output 25, 70, or 100 volt to accommodate distributed audio systems, making this the perfect power amp for countless installed in-ceiling systems. Add QSC sound quality to your system with the ISA 500Ti!

QSC ISA 500Ti Power Amplifier Features at a Glance:

• 2 x 260W @ 8 ohms, 2 x 425W @ 4 ohms, 2 x 700W @ 2 ohms
• Low-impedance and isolated 25, 70, and 100 volt outputs for distributed audio systems
• Rear panel gain controls with 2dB detents for quick and repeatable settings
• XLR and detachable Euro style input connectors
• DataPort V2 for use with DPV2-compatible signal processing accessories (XC-3, SF-3, LF-3) and DSP-3/DSP-4 (with external power supply)
• Independent defeatable clip limiters for reduced distortion
• 50Hz or 75Hz selectable highpass filters protect speakers and prevent speaker transformer saturation with minimal effect on program material
• Front panel indicators include power, signal, and clip
• Covered barrier strip output connectors for safety agency compliance
• Automatic variable-speed fan for quiet normal operation with maximum cooling on demand
• Rear-to-front air flow keeps equipment racks cool
• Stereo, Bridge, or Parallel operating modes
• Comprehensive protection circuitry including DC, infrasonic, thermal overload and short circuit protection
• 25, 70, 100 volt, and low-impedance outputs available simultaneously
• Simple barrier strip connection determines output mode