Try a tube based buffer, like a VHT Valvulator 1or any tube based buffer, it will hit a power amp in a magical way.
Your Power Stage will have no choice but to sound 100% like a the amp !!!!
To be fair, it isn't the clean power that makes it sound like the amp...it is what it is connected to. If you have a great modeling system that models tube amps really well (Fractal, Kemper, quite a few others these days), the PowerStages will just make that modeled sound louder.