Allan, I relate all too well to that silence you refer to.
When we lost our first Yorkie, coming home from work that first day and not being greeted by the crazy barking and a squeaky toy was as devastating as the experience of putting him down. (He had cancer.)
I couldn't imagine ever having another one. In fact, I strongly resisted getting one. The horrible end experience consumed me and I felt there was no way I could do that again, EVER.
At the end of the first week after Scruffy's death, I got suckered into "looking" at puppies. When the breeder offered me a puppy to hold, I reluctantly accepted ... and the rest is history. I think of it more as Ozzie picked me as he lovingly nuzzled my shoulder for hours as we looked at puppies, looked at their parents and negotiated. It became pretty clear pretty quick that I wasn't going home without him!
Ozzie and Scruffy are like night and day. But each came with their own blessings and idiosyncrasies and I feel fortunate for having both in my lifetime.
I don't know what your experience would be, but I can guarantee you tow things:
First, you will NEVER replace Zack. But when you feel the time is right, definitely do yourself a favor and get a new little friend to channel some of that love into.
Second, you will not only have a place to send that love that you currently can't direct, you will get so much love back.
Good luck to you as you learn how to deal with this tremendous loss. Thoughts and prayers are with you from many YTers who have lost their furry friends, too.