SVS Prime Bookshelf vs Klipsch RP-600M II
The short answer
Buy the Klipsch RP-600M II for the deeper bass floor on the one yardstick both sheets share: 44 Hz against 48 Hz, both stated at ±3 dB. Buy the SVS Prime Bookshelf for the shallower cabinet, 9.4 inches against 13, and for the only sensitivity figure on this page whose row stores a measurement environment. The 94.5 dB against 87 dB reading decides nothing either way — the Klipsch's context is UNSTATED in our data and the SVS's is anechoic full-space, and we never rank sensitivity across contexts.
One sold direct, one through dealers, both priced by the left/right pair in our catalog ($700/pair vs $700/pair as tracked today). The interesting part is that only one of the two ROWS stores how its sensitivity was measured — and the reason the other does not is on its own spec sheet.
Reading the numbers honestly
This is the rarest thing in a speaker comparison: one of these two rows stores a measurement environment. SVS publishes 87 dB at 2.83V/1m, and our row stores the acoustic environment behind that figure — anechoic full-space — beside the value. (Our context field carries the ENVIRONMENT only: a stated drive level like 2.83V/1m is kept as a record note, because 2.83V is 1W into 8Ω but 2W into 4Ω.) The Klipsch's 94.5 dB is stored with its context UNSTATED, and the reason is worth stating plainly: its sheet DOES footnote the figure — 'SPL at 1M, half-space anechoic with 2.83V input, in-room sensitivity' — but that footnote names a half-space measurement, and half-space has no value in our enum (in-room, anechoic full-space, unstated), so nothing was written rather than a guess between the two conditions the same sentence names. Our normalization rule for exactly this case is explicit — never rank a sensitivity figure across measurement contexts — so the printed 7.5 dB gap is flagged here rather than ranked, and nothing below rests on it. That footnote is a hint about which way the figure leans — an in-room reading typically sits a few dB above the anechoic standard — but a hint is not a stored context, and we do not subtract a few decibels from a number to make a comparison come out. The bass floors ARE like-for-like for once — 48 Hz (SVS) and 44 Hz (Klipsch), both stated at ±3 dB — so the Klipsch's four extra hertz is a genuine same-yardstick difference. On impedance the two are equally uninformative: both state 8Ω nominal and neither states a minimum, so neither sheet lets you check a worst case. The practical split is the cabinet: 9.4 inches deep and 15.5 pounds against 13 inches and 18.1 pounds. Both rows record a rear port and both need wall clearance, but only the Klipsch's enclosure-type and port-location fields are manufacturer-stated — the SVS's pair is Estimated in our data, so confirm the clearance before you plan the shelf.