GR-Research Klipsch RP-600M Upgrade Review: Rated 3.2/5

Last updated: October 30, 2026

The GR-Research Klipsch RP-600M Upgrade is rated 3.2/5 for sound quality, #179 of 222 Large Size Bookshelf Speakers. See all Passive Home rankings for every top pick.

GR-Research Klipsch RP-600M Upgrade · Editor's rating 3.2/5, ranked #179 of 222 Large Size Bookshelf Speakers
Check price at GR Research ($279 per pair) →

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Brand: GR-Research

#179 GR-Research Klipsch RP-600M Upgrade: $279 per pair GR Research $279 eBay

Pros: A DIY crossover kit that fixes the main flaw of a popular Klipsch bookshelf speaker, with smoother sound and all new parts. GR Research’s replacement crossover fixes the stock Klipsch RP-600M’s biggest flaw, a deep response dip around the crossover, by using gentler first-order filters. Audio Science Review’s measurements show listening-window smoothness rising from 0.40 to 0.78 and the preference score from 3.66 to 5.11 (5.61 to 7.06 with an ideal subwoofer), with response within 3dB from 80Hz to 20kHz. Bass reaches 68.8Hz at -3dB and about 40Hz at -10dB, and the kit also cuts ringing around 800Hz. At $279 per pair it comes with all new crossover parts, No-Rez damping, wiring and connectors. Measured bass extension of 68.8Hz (-3dB), with a measured sensitivity of 86.7dB.

Cons: This is a DIY kit, not a finished speaker: you need a pair of the original Klipsch RP-600M, which is discontinued, and must rebuild both crossovers yourself. It does not fit the Klipsch RP-600M II. Sensitivity drops about 1.5dB to 86.7dB, horizontal directivity narrows for a smaller sweet spot, and a 4.44 directivity-index deviation shows uneven off-axis sound. Average on-axis deviation of 0.49dB is rougher than the stock speaker’s 0.23dB, and the current Klipsch RP-600M II scores higher (5.64) with no work at all.

Featured on:
ReleasedJun 2022 (4 years ago)
Bass Extension (-10dB)40.0Hz (measured, spinorama.org ASR data)
Bass Extension (-3dB)68.8Hz (measured, spinorama.org ASR data)
DIY KitYes
Dimensions15.7”H x 8”W x 11.9”D (398.8 x 203.2 x 302.3 mm)
Drivers6.5” Cerametallic cone woofer, 1” titanium LTS vented tweeter with Tractrix horn (stock Klipsch RP-600M drivers)
Sensitivity86.7dB (measured, Audio Science Review)
Spinorama Preference Score5.11
Spinorama Preference Score with Perfect Sub7.06
Weight16.1 lbs (7.3 kg) each
Woofer Cabinetported
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