Kenwood KMR-M300BT
#7 in Gauge-holeFull review
A full-featured gauge-hole stereo for a small boat or powersports dash. Spend more on the eXcelon KMR-XM500 only if you want its 5 V pre-outs and longer warranty.
Amazon $299$299
The Kenwood KMR-M300BT is the better marine stereo overall, rated 2.6 to 2.4. The Kenwood KMR-M300BT leads on features, water rating and pre-amp outputs. The BOSS Audio MGR300B costs $169.01 less ($129.99 vs $299).
Prices were last checked November 9, 2026. Product prices and availability are accurate as of that date and are subject to change; the price and availability shown on Amazon or the retailer's site at the time of purchase apply. As an Amazon Associate we earn from qualifying purchases.
BOSS Audio MGR300B
#9 in Gauge-holeFull review
A cheap gauge-hole Bluetooth stereo for a jon boat, golf cart or UTV. Its IPX5 rating covers splashes, not heavy spray.
Amazon $129.99$129.99
Which should you buy?
- Choose the Kenwood KMR-M300BT for features (SiriusXM-ready, weather band, Bluetooth, USB playback vs Bluetooth, USB playback), water rating (IP66 front vs IPX5 front) and pre-amp outputs (3 RCA output sets at 2 V vs 2 RCA output sets).
Scores side by side
Each factor is scored 0-100 against the same fixed reference points for every gauge-hole marine stereo; a clear win is highlighted. How we rank explains each one.
| Factor weight | Kenwood KMR-M300BT | BOSS Audio MGR300B |
|---|---|---|
| Overall rating | 2.6/5 | 2.4/5 |
| Amplifier power 20% | 19 19 W RMS x 4 at 4 ohm | 50 RMS power at 4 ohm not published (neutral score used) |
| Zones 15% | 0 single zone | 0 single zone |
| Pre-amp outputs 10% | 29 3 RCA output sets at 2 V | 14 2 RCA output sets |
| Features 25% | 50 SiriusXM-ready, weather band, Bluetooth, USB playback | 20 Bluetooth, USB playback |
| Water rating 10% | 70 IP66 front | 40 IPX5 front |
| Display 10% | 58 2.7 in color | 50 display not published (neutral score used) |
| Warranty 10% | 0 1-year warranty | 0 warranty not published, scored as none |
Specifications
| Kenwood KMR-M300BT | BOSS Audio MGR300B | |
|---|---|---|
| Audio | ||
| Amplifier power (RMS, 4 ohm) | 19 W x 4 RMS | - |
| Zones | 1 | 1 |
| RCA output sets | 3 at 2 V | 2 |
| Sources and control | ||
| Bluetooth | Yes | Yes |
| USB playback | Yes | Yes |
| Phone app | No | No |
| SiriusXM-ready | Yes | No |
| NMEA 2000 | No | No |
| Wi-Fi or AirPlay 2 | No | No |
| Weather band | Yes | No |
| DAB+ | No | No |
| CD player | No | No |
| Camera input | Yes | No |
| Build | ||
| Mount | Gauge hole | Gauge hole |
| Front water rating | IP66 | IPX5 |
| Display | 2.7 in color | - |
| Warranty | 1 year | - |