The "L" in your amber malt is not refering to Liquid. It is refering to the Lovbond scale. The Lovibond scale is a system used to describe the color intenaity of beer. At 35L you should be reciving some nice color. But if I have used Amber DME when making my IPA. But it just depends on the clairity at which you would like your IPA to appear. And as far as the undermodified Pisen, I have not used is, but as far as I read it would not be a bad choice.
Good luck in your beer. I love IPA's. Let us know how it turned out.
Primary #1:Apricot Amber
Primary #2: Dry Hopped Amber
Secondary #1: Nothing
Bottles: Head Butt Pale Ale, Vanilla Cream Porter, IPA, Wee Heavy Scotch Ale, Aventinus Clone, English Brown
Planning: Peach plambic, Summer Shandy