I'm wondering if I should get the new HK avr 1700 or should I stick my current HK avr 254?
I like good, clean sound. which one sounds better.
They share the same amplifier topology, but the 254 uses a more traditional, big and heavy power transformer with ample secondary/reserve capacitance. The new 1700 uses a SMPS, hence the MUCH lighter weight and reduced power consumption.
The 254 was the last US model HK to be rated and marketed/published in their traditional fashion, a continuous average of ALL of the amplifier channels (in this case seven) being driven simultaneously 20hz-20khz into 8ohm loads with less than .07% THD. The 254 was spec'ed at 50watts for each of it's seven channels in this fashion. Newer generations stray further and further from the HK tradition - 2 channel only ratings, higher distortions, single frequency tone, etc.
The x54 and x550HD model HKs were also the last to feature dual secondary power supplies, separating power for the C/SR/SL and FR/FL/SBR/SBL channels.
The specs for the new 1700 have changed already, and as usual there are some discrepancies between literature. The manual states 100W per channel, with 2 channels being driven at "6/8ohm", at 1khz, with less than 1% THD.
<.1% THD is also spec'ed in some literature and a completely different rating of 95W per channel, two channels driven @ 8 ohms, 20Hz - 20kHz <0.07% THD can also be found on the website.
What type of speakers are you driving? With harder to drive inefficient speakers (especially if full range) - I feel the older 254 would be a better performer. I have no experience with the new 1700 - just my personal opinion. The HKs of past were known to be of few that could meet, and often exceed their specifications.
Again, the amp topology for each channel is the same, it is the power supplies that are completely different. The sound should be nearly identical with low demand material, when the amps are pushed is the question.
Note - The 1700 boasts several newer technologies over the 254 - internet radio, DLNA network playback, DPLIIz, 3D support, Airplay, Android and iOS device app control, USB playback, etc. Of course several more HDMI inputs (at the loss of obsolete legacy analog connection) If that is important to you, the 1700 would probably make a better choice. If not, you already have the 254 - might as well stick with it.
I have been using a 254 in my smaller system for several years. It has been rock solid, an awesome performer, and I have no intention on replacing it.
Also, despite being several years older, the 254 has the much nicer HD on-screen GUI which is still being used with minor changes in the current 2 and 3 series models, along with transcoding and upscaling of any analog video input to the HDMI output.
The 254 also has SEVEN amplifier channels vs. the 1700's five. This also means more post-processing options to create a 7.1 presentation from 2 to 5.1 channel material.
-that I can plug my sub (klipsch sw-350) to the back of receiver to power sub when avr is on
The AVR's switched outlet is only for powering LOW wattage components, note the 50watt max specification. You should not plug a powered subwoofer into this outlet.