Is your 550 a better-sounding one than my S450DLX, Mario? I don't know if you've spun dial on one of those. It's the model with the red on-off button.
I got the 450 a few years ago at Radio Shack, from back when they actually knew what a radio was, and even sold some. $70 was the price.
Mine has separate treble and bass knobs, but the speaker sounds as though it's the diameter of a bottlecap. Plus, the unit has this 'breathing' audio -- best as I can describe it -- as though some AGC component is wound up too much.
The 450 did give me one great Mid-Winter Anomaly catch -- WCFR 1480 from Vermont. The how-far-is-it page says 260 miles. 1480 has been a blank frequency here for over 10 years, since WISL Shamokin went dark.
But that was outside, in a big parking lot, about 2PM, with batteries, amid a snowfall ; me waiting for the ladies to get done grocery shopping. (Lol -- there were some young folks outside the employee door taking a smoke break. They dispatched the most courageous of the bunch -- and the biggest guy -- to see what this suspicious situation was about, what this goofball was doing, waving some alien black box around with a red button and listening to static in their parking field in the snow. I would venture that explaining what a *radio* is nowadays to someone around age 20 is next to impossible. It might take even longer to explain what 'AM DXing' is :- )
In any case, the S450 is useless in the house. Plus, it sounds lousy. Do you find the 550 sonically sufficient?