You certainly do! First of all, HPLC-grade reagents generally have had particulate matter filtered out. Even if you routinely filter your solutions, though, you still need HPLC-grade. Example: ACS-grade phosphate and methylphosphonate reagents contain impurities that absorb light at low wavelengths. They accumulate on some types of HPLC columns during equilibration with the starting mobile phase and then elute during the gradient, resulting in a large, artifactual peak. HPLC-grade reagents generally have these impurities removed.
if you can't find an HPLC-grade salt but the corresponding acid is available in HPLC grade, then prepare the salt by adding the purest grade that you can find of the appropriate base to a solution of the acid.