Do I need to use the original Seq AC adapter?

One important hint for a long relationship with the Seq :) - you can power the Seq up both from the USB port and the original AC adapter. You may like to mark the power plug of the AC adapter because the Seq is operating at +5v and is very sensitive for the higher voltages, it's easy to damage it with the use of an improper AC adapter.

Answering your question, yes you can. But please make sure that before connecting it to your Seq unit you've double-checked that it has identical powering voltage and amperage properties!