The simple prefixing or sufixing of the real password with a salt relitivly pointless. The only function it serves is to increase the character length of the password.
In the scenario where this type of attack can occur the attacker A: has access to your live DB or B: attacker has a many stolen hashes C: attacker has only one stolen hash.
In A you are already screwed.
In B and C you have a bigger problem and are only trying to delay the attacker long enough that the hashes they have are not valuable.
If the attacker has multiple hashes a prefix/suffix salt does no good. Because after the attacke cracks two hashes:
it is clear what the salt was. It is what is common between them: abc$123.
If the attacker only has one hash it only delays for a while. If the cracked hash is (*%6ILikePoneys76
The attacker has it's safe to assume that ILikePoneys is part of the password. Leaving less then 7! likely combinations.
Salting by rehashing the original hash will increase the time to crack, but only by double. If the hashes are cracked and they look like giberish, it's safe to assume they were rehashed. So rerun the cracking tool and if the subsiquent cracked hashes are things like:
you immediatly know the formula is username + '%$' + password.