Gemini, from your description it looks like
a) your amp doesn't drive the spkrs (I checked the Seconda tech specs they are not the easiest to drive)
b) there is something wrong with the mid-bass units. You would have noticed that, so this is an unlikely option
c) there is something seriously wrong upstream -- also unlikely as the sound is OK with the Triangle.
The Seconda is a close design which makes it a tad less easy to drive.. can you borrow a bigger amp to try on them?
a) your amp doesn't drive the spkrs (I checked the Seconda tech specs they are not the easiest to drive)
b) there is something wrong with the mid-bass units. You would have noticed that, so this is an unlikely option
c) there is something seriously wrong upstream -- also unlikely as the sound is OK with the Triangle.
The Seconda is a close design which makes it a tad less easy to drive.. can you borrow a bigger amp to try on them?