I ain't no expert, but I know how to google :3 I've seen the A151 pop up on Head-Fi a few times, this is from the headphone buying guide:
"Full warm sound. Full bass, clean smooth mids, clean highs. Build quality is great, no microphonics."
As for the T1S, only one review from what I've seen: http://forum.xda-developers.com/general/accessories/review-ttpod-t1s-ear-headphones-line-t2888834
From a glance, the A151 has a single balanced...