I've neglected my Pandas since about a week after I bought them when they were first introduced. I'm not a fan of the mid-range tuning and the internal amp is not up the challenge of delivering the authority and impact I love. So, I put them back in their case and put them back on the shelf... until today.
Today, I pulled them out, ignored the internal amp, connected the 3.5mm cord and plugged them into my Emotiva BasX A-100, EQ'd to taste (which for me is dropping the upper bass/lower mids about 4db, low Q, centered around 400hz) and cranked them up.
With the muscle of the Emo driving them and my EQ tweak, they're a completely different headphone. Extraordinary impact and power handling. I never play music loud for long, but, like a muscle car, it's fun to do short term acceleration runs like on-ramps to see what they're capable of. For me, once I've dialed in the FR, it's about the ability to deliver authoritative lowe end impact without distortion or breakup. Most headphones can't take it and either compress (Sennheiser) or XMax out (Focal). Some can take it and deliver full frequency SPL without failing.
The surprisingly small driver in the Panda is a marvel. I had no idea it could deliver what I asked of it today. If DROP offered an analog-only version of the Panda for $199 and bundled or suggested a powerful single ended amp, they'd please another segment of happy customers. I don't know how big that segment is, but it has at least 1 member.