I've been thinking of this for quite a while, but I've decided to post some of my thoughts on now my characters sound in my head.
Intelligent Design
Intel is, despite his protests, a posh noblepony in upbringing, and his speech betrays that somewhat. Not only that, he is a noblepony scholar, adding a bit of insufferable genius to it as well. In my mind at least, he has the voice of David Mitchell, posh and smartlike.
Warm Threads
This was the pony that made me start thinking of speech, if only for the fact she doesn't stop. It is very very easy to imagine her rants in the voice of Pinkie Pie, but I don't. Not really. She's a toymaker, yes, but she's a stuffed toy maker. My mind regulates the role of seiyu to Kana Hanazawa, if only for Renai Circulation.
Something Nameless
Emotions- Restrained. Etiquette-Emphasised. Duty-Everything. If you want to know what Nameless sounds like, remember those three things. Minori Chihara is who I imagine her sounding as, lacking in feeling in speech.
Elegance Design
Ooh, boy. Little Elegance is the one I have not got a person for. But I do know what I want her to sound like. You know the idealistic princess type charcter that believes that there's good in every heart and that everyone can all get along if they tried? Yeah, I want that voice. Saying the hateful things that Elegance says.