Every AC source has different issues so it's not as simple a question. If your in a single dwelling it defiantly pays to add dedicated breaker buss or at least some dedicated breakers. Since digital devices are generally susceptible to RF and EMI metal clad runs from the breaker ending with shielded cables can be beneficial.
After these somewhat inexpensive measures auditioning conditioning devices could improve the AC, sometimes not.
After these somewhat inexpensive measures auditioning conditioning devices could improve the AC, sometimes not.