I became curious and looked it up, the Creek 5350 seems like a pretty decent offering. Unfortunately it has a small footprint on the internet.
Grado doesn't currently have any cabled models with 100 in the model number. They made a SR100 back in the 90's, is that what you tried?
Anyway, the only hint I could find was here:
https://www.head-fi.org/threads/is-creek-5350se-a-good-headphone-amp.85855/
https://www.head-fi.org/threads/ipod-unamped-vs-tah-04-vs-creek-5350se.59019/
One poster loved the headphone match with the Sennheiser HD650, or did you see that already? Anyway, hope this helps.
Grado doesn't currently have any cabled models with 100 in the model number. They made a SR100 back in the 90's, is that what you tried?
Anyway, the only hint I could find was here:
https://www.head-fi.org/threads/is-creek-5350se-a-good-headphone-amp.85855/
https://www.head-fi.org/threads/ipod-unamped-vs-tah-04-vs-creek-5350se.59019/
One poster loved the headphone match with the Sennheiser HD650, or did you see that already? Anyway, hope this helps.