Review: Krell KSA-150 Amplifier

Category: Amplifiers

Years ago I had the opportunity to listen to a Levinson system at Difinitive Audio in Seattle that made my jaw drop. If you closed your eyes the performers were in the room with you. Jazz was Jazz, Rock was Rock, Classical was Classical. Everything was just perfect. The way it should be.
Realizing that I just could not afford a $100,000 system, my seach started. Sound familiar? I worked my way through a number of system variants and wound up with Cal Audio Sigma and Delta source (getting a little long in the tooth now) a Krell KSP-7B preamp, a much modified Adcom 555 and my Acoustat Model 1 speakers. I had been very happy with the sound and the resolution of detail my system was able to produce. It just did not have the authority or control I had been looking for. I also knew the 4 ohm impedance Acoustats were just not an easy load to drive with a combination of electrostatic pannels and woofer module. The Adcom had to go. Since I would be buying used I did a lot of home work. With no auditioning at home before you buy, I called a LOT of friends. I really liked the sound of the Krells I had heard, knew of their ability to double power down to 1 ohm and what the heck they would match my preamp. I finally settled on replacing my Adcom 555 with a Krell KSA-150. (Plateau biasing, 150 watts/channel doubled down to 1 ohm). I purchased it for $1750. When it arrived I found what I would eventually call the amps only draw back, it's weight. At approx. 90 lbs get some help to move it. I understand completely why Krell also puts handles on the back of the amp. I placed the KSA-150 on my amp stand and I hooked the amp up with (used) MIT Proline balanced interconnects, two separate runs of (used) MIT T2 speaker cables. All the connection points seemed robust, with the detachable power cord a good feature. OK I'll catch hell for this but my amp stand is a well built old antique commode filled with sand. Don't knock it, it works and DOES make for a conversation piece. Since used means no break-in period, I turned it on and let it warm up. The soft start is a nice feature that doesn't dim the lights like my Adcon did. When I came back to the room the differencs was not subtle. Bass authority was astounding with no sense of strain. Detail resolution was significantly better. The immage now had better focus and front to back depth with overall smoother sound. I no longer have to wonder if it's an acoustic bass. One of my favorite albums (sorry I just dated myself)........ CD's is Norah Jones. The music just sounds right with silky smooth vocals and a wonderful piano. Those who have the oportunity to attend a LIVE symphony .... do so for comparison and enjoyment. If you can clearly hear the separate instruments as I can now and they are not a blurr playing the same note you are on the way. With the right material you can forget it's recorded. The addition of the Krell KSA-150 made the musical experience more real and enjoyable and I have no urge to update my amp having lived with the KSA-150 for six months. With Krell's reputation for taking care of their equipment, build quality, and sound, the KSA-150 is a keeper. I would recommend a good used KSA-150 to anyone looking for a quality amp (new or used)in $1500-$2000 price range, especially if they have a difficult load to drive.

Associated gear
Krell KSA-7B
Cal Audio Delta transport
Cal Audio Sigma D to A
MIT interconnects
Acoustat Model 1 speakers

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I've had the KSA-150; nice amp and very well built. I later went to the Classe 15 which, to my ears, sounded better and ran a lot cooler.
Just a quick note:
replaced a friend's 200w Accurous with the Krell KSA 80B and it must have been like the
adcom to Krell experience. I had a GFA555 before Mcintosh, spectral and Pass Labs. but, i say it must have been the same as it was really profound, as one would expect.
Heavy amp, big odd heat sinks. Slightly cheap binding posts, I don't like plastic cappings, but it was extended in highs and lows and clean through out. Had somewhat of a hum.