Sorry to take it off-topic, Jason, but there's a lot more to good amp sound than a high damping factor (or "specsmanship" generally - be it distortion figures, rated RMS power, etc). It's even debatable whether one can actually hear much difference beyond a factor of about 20-100 or so, depending on woofer size. Also, keep in mind that the real-world damping factor is not determined by the amp alone, but by the amp/cable/speaker system, as well as the instantaneous signal (music program) content being played through said system (in other words, the factor will vary with frequency). The damping factor determinant, as far as the amp goes, is its output impedance vs. frequency, with the lower impedance resulting in the higher factor. But ultra-low amp output impedances are most easily achieved primarily through the liberal use of high levels of overall negative feedback in the circuit design (or a large number of paralleled output devices, something that won't apply to your integrated), which in high-end practice is commonly considered to be degrading to sound quality. In addition, the above-quoted damping factor (BTW, did an extra zero get attached to this number? 1,000 is more typical of a high example) will apply only to an idealized 8-ohm speaker load; your Thiels, for instance, go as low as about 1/4 that figure, a condition your amp likely wasn't designed to cope well with, and I'm betting is not rated for in its literature.
You are absolutely correct to assume that I don't know anything specific about your particular amplifier model. But I am familiar with Kenwood as a brand, and am also a Thiel owner. As someone who upgraded his speakers first (the good way to go, IMO), and slowly followed with a progression of increasingly better amplifiers, I can tell you from experience that your speakers are better than your current grade of electronics will allow them to show. Your 3.6's and 4A's are large, demanding speakers that are very accurate and revealing, and will require prodigious amplifier output capability *and* quality to give of their considerable best. The Thiels feature a hard-to-drive low-impedance reactive load, with a complex crossover and lowish sensitivity which drain power and kick a lot of back EMF into an amp's output section (and also demand careful cable-matching). And even though the Vandy's, for instance, weren't terribly expensive speakers, they will mate profitably with higher-quality electronics (take a look at Jvogt's equipment list above as an example of high-end gear being beneficially used to drive a moderately-priced yet transparent speaker model - not that you'll necessarily need to go all ML in your system!). Since both of these speaker models are physically large, with first order crossovers, they need to be listened to from a good distance in a large room in order to perform properly, which will demand large power reserves on the partnering amp's behalf to achieve realistic volumes. The design and construction of a "mass-market" integrated like a Kenwood, or even more upscale "mid-fi" brands such as NAD or Adcom, are not able to take advantage of the full potential of such speakers. Upgrading cables will of course also be an important part of realizing this potential, but before selecting a cable, you may want to seriously investigate better, amplification options (as budget allows, of course), auditioning candidates in your own system if possible. If you upgrade the amp first, then you'll have a much better basis with which to make a compatible cable selection, as it will permit you to hear back into your signal chain much more clearly.
I know that the sort of unsolicited advice to upgrade a component you enjoy which I am offering here can be taken as an unwanted pain in the you-know-what - and I wouldn't blame you if you did. But if you never have (and even if you aren't planning on buying something anytime soon), I urge you to find a dealer you can beg or borrow a home audition from of something in the way of high-quality, high-power SS power amplification that they recommend to drive your speakers with (and maybe some speaker cables to go with it). It could prove to be a truly ear-opening experience. Happy listening, Z. :-)